Growth Inhibiting Hormone

Now that Wattley Discus is considering Simply Discus Forum home (isn't every other forum just green with envy), perhaps Gabe and/or Jack would care to share their beliefs, and what these beliefs are based on, regarding GIH and discus. Jack spoke of this when I saw him on Long Island and has mentioned it in his TFH column, Gabe replied to an email I sent about a year or so ago when this topic was being discussed on DPH Forum. I am most curious if this is a theoretical belief or is there empirical studies to back it up. If theoretical, what observations have been noted to suggest that this hormone exists? If empirical studies have been done, by whom, and is the data available?

Ha, this is too much. Now a question can be asked directly about many of Jack's ideas and they can be answered for all to read.

Thanks,
Mat

[JacKWattleyDiscus]

Hello Matt
The GI Toxin or Hormone has been in play for the longest of times. We have run physical experiments sometimes planned others accidentally. Each and every time the smaller fish in the tank even from different strains have just fallen behind and become stunted. Hobbyists today always call the hatchery asking why their smaller 3" discus aren't growing as big as their 5" single fish after 1 years time.
The experiment is being experienced by all who are mixing different size fish every day and don't know that the GIT exists. And no you cannot remove it by doing water changes. I do those on a daily basis and it does not help.
If more true scientific research was placed on the discus community, so much would be revealed. Without the scientific proof we have to accept the results and theorize on the why's.
Can you immagine one little scientific experiment that told us that by adding a little something to our tanks it would diffuse it.  ::) Whishfull thinking.
To shed some light to the rest of the hobbyists, try to purchase and maintain all the discus in a tank of same size to avoid this problem. If you have different sizes in the same tank, get another tank. Heck that's how I did it, except that now I have 326 tanks and too much work. :P
Gabe

[scotz]

Gabe - just a thought here - since it would be impossible to have all of your discus the same size - do you think it would be wise?? to put a smaller "cull" discus in with a GROUP of discus so he would become the runt and not one of your better fish??

scotz

[daninthesand]

Hi Mat.

I am in no way an expert on this topic however I have recently noticed that moving my smaller fish to a tank with like-sized fish has made a difference. It seems the little guys catch up. I used to think it was competition for food, however the little guys were easily eating just as much as the bigger guys. And I also have it from another reliable source who told me he has seen the same thing many times in his years as a discus hatchery owner.

HTH Dan

I am a believer in GIH or GIT. To convince me is not the problem here. I wanted it to be printed here for all to read directly from Wattley Discus and not paraphrased by 2 or 3 or 18 different people until it no longer resembled the original statement.

As for putting a cull discus into a tank to become the runt, that would not work. The toxin/hormone works on all the discus not a selected target.

Thanks for responding Gabe.

Mat

[Steve_Warner]

Hi all,
This is an interesting concept to me. I have a few questions regarding this. If discus put out a growth-inhibiting hormone, do they all put it out against each other and why aren't all discus in the tank affected by each other's hormones?  Do a few suppress/overpower the hormone and have growth spurt?  Is it just that the bigger one's produced a little more of theirs than the other discus'? How is it that there is only one(or a few) ultimately affected and not all EXCEPT one dominant one. I can see the definite possibility of this as it occurs in the plant world, I believe.    Hmmm, too many questions.     Very interesting!

                                                           Steve

Sir,

I too, find this is an interesting issue and if it is due to hormonal inhibation, have you any suggestions on doseage and time course?

Could daily water change reduces the hormone level or better still, with a continue dip system would have removed most hormone? Therefore, the say "hormonal effect " would have been diminished?

Could the growth be explained statistically with Normal distribution curve (Gaussian distribution). That you always find the extreme at either ends of the last 2.5 percentiles, taken it is a 2-tailed p?

Thanks and regards
Martin

[Kagan]

Hi there,

 I do not agree that a hormone or toxin is the reason that inhibits the growth of a small discus between the big ones. It may be stress, being chased and as a result of this; spending the energy for "running away", not for growing. Also, we know that smaller fish gets less food than the others. So they get less energy to be used in their body. Not all the fish becomes runt because as these fishies are alive, I think every one of them have a character as we, humans. So some of them do not have "courage to fight and resist" and some of them have. The ones that do not have courage are stressed more. So, as time passes, they do not grow well as a result of their less energy is spent for running. What do you think??

Kagan

[brewmaster15]

Great Topic Mat, and great info all.
* *Steve -- you are 100% correct that this occurs in the plant world. *Keep in mind though its used to keep seedlings from out competing with *parents *plnts here, or may give the larger seedlings and edge *in growing compared to others.
* I believe that hormones *play a roll *fish tanks, definetly *for spawning, *maybe that same hormone *is responsible *for the growth inhibition many see. Your guess is as good as mine here. *If so I think its by accident, a non *intentional thing , that does not occur in the wild. My reason for feeling this way is because the waters were these fish evolved are *vast *and any hormones are diluted away, *even the reproductive ones I feel are of limited range,which is why fish rely heavily on attracting mates by the colors and patterns and motions.
* *Just playing the devils advocate here *but its very *possible that the growth differences *observed are the result of *food competition and activity levels. *The larger fish eat more and *aggressively defend areas. This would build more muscle mass. this growth in turns sparks *hormone cascades with in the fish that *stimulate its own growth inexcess *of the tank mates.
* The only other *problem I see *with the growth Inhibitor idea is that it would affect all the fish except maybe the one *putting the hormone out, as it might have other hormones * that are elevated and counteracting it.
*This *is of course speculation , *and I offer *them only as an alternative explaination for what is being seen.
* Keep the good discussions *coming all, this is great!
Take care,
al

[DarkDiscus]

I've seen this take place with several different species of cichlids and agree that aggression may play a part, but I've seen it in good sized tanks with really small cichlids which aren't aggressive and aren't in competition for food.

Likewise I've seen it in divided tanks with 3 fish where there is no aggression and no competition for food at all.  One of the 3 lags behind in growth.  

I agree that there is a hormonal effect.

Would a continual drip system work to dilute the hormone?  It seems likely if the turnover was high enough.  Obviously, as Al mentioned, this wouldn't occur in the wild, as the hormone is dissipate immediately.  If you could have high enough flow rate to get rid of the hormone immediately, it would work.

My 2 cents.

John

[JacKWattleyDiscus]

Hello
We have run experiments on central systems similar to the artificial breeding system that Dan displayed on the "Visit to the Wattley hatchery" string.
6 20 gallon tanks, strapped to a central filter.
60 fish total 10 per tank. Smallest 5 cm, largest 9 cm and all other sizes in-between.
Here the larger fish could not chase the smaller fish, everyone ate the same amount of food and received the same water changes.
After 6 months we had to pull some of the larger fish , as some actually paired off and others were just to large to keep together. We left only one male in the tank. After 1 total year of running the experiment, the male was 6" (15 cm). The largest fish we were able to grow was  a 4"  single male in a tank 3 over from the large male. The rest of the fish (49) were between 5cm and 7 cm. All looked as I like to call them owls.
To answer a few questions,
all smaller fish are affected not just a single cull or runt.
Water changes will not wash it away, it is being produced constantly, much like we breath out CO2.
Fish of similar size are not affected.
Once in a while a fish or two do grow a little which people say disproves the GIT theory. These are rare cases. Just like people that smoked all their lives and lived to be 100. But, just think ::) how old would they have become if they had not smoked ;D
Same holds true with these smaller growing fish. They could have been the giants, had they not been held back.
People we are all hobbyists and biologists all in one.
I urge people to run their own experiments and report back. I realize that these experiments are time consuming, but I bet a ton of hobbyists have been running these experiments over the last year without realizing it. Please give us your results. The more people who share, the more information we have to theorize with.
Gabe

I certainly can't disagree with the concepts described here but it is possible that the cause of the size difference is not a growth inhibiting hormone.  You are looking at the results i.e. the differences in the growth of the fish, and reaching the conclusion that the cause is a GIH.  I'm no biologist but is there such a thing as a documented GIH in any fish species?  

The aspect of this that doesn't make sense to me is that the GIH doesn't affect fish of the same size.  Why would that be?  You'd think that if you overstocked a tank with 3" fish that the level of the GIH in the tank would be so extreme that none of the fish would grow.  And if you compounded it by doing weekly water changes instead of daily then definitely none would grow.  But I've repeatedly seen customers of mine with tanks as I describe where all of the fish grow well.  So it confuses me that the GIH would only affect smaller fish, it should affect all fish if the concentration is high enough... even the largest fish putting out the most GIH.  I'm not arguing the concept, just trying to understand.  And I don't have any alternate theories to put forward.

While it's possible that the cause is not GIH, it may not be important what the cause is if the documented solution is to keep like-sized Discus together.  That raises the issue of what is a like-sized Discus.  I got 7 new fish awhile back that were about 1.5-2" in size.  They've been growing really fast with the water changes I've done & cbw they've been fed.  Now there are significant size differences between the largest & the smallest.  As much as an inch in difference.  Should I plan on separating them soon?  At what point is the size difference significant enough to separate a fish?  I can't do it at all at this point since they're still in quarantine but it seems no matter the group of fish I put together there are always slower growers & faster ones.  The ability to own enough tanks to separate fish into tanks with like-sizes could become pretty unwieldy.

Dave

[Mike_T]

Great info. What about discus raised together form the same spawn? Usually males grow larger than their female siblings. Often the females catch up later, but seem to mature sexually at an earlier age. Do you think this hormone may not be active until sexual maturity? If one discus takes off in size, do you think he could emit this GIH to keep his siblings from catching up to him? It seems that this doesn't occur, as most will eventually catch up in size. Just a thought. I'm very curious because I'm thinking of putting some 4"ers into a tank with a few wild adults.

I'm also curious that if there is a GIH secreted by discus, do you think it could be diluted in domestics after years of being captive bred and inbred, where these hormones really would not be needed?

-Mike T

[daninthesand]

Hi every one.

This subject of GIH is an intersting topic. I was wondering how this homone would ever even develop from an evolutionary point of view. If you assume that in the wild this homone is so dilute that it is not noticable then how did it develop in the first place? and why?

You could argue that in times of drought or low rainfall this hormone builds up in the river system, not in the grand scheme, but in isolated areas of poor water flow etc.where discus concentrations are higher than normal. Clearly this would have an evolutionary advantage of boosting the survival of the fittest. In this scenario, who is the fittest? Is it the largest fish? Perhaps, since they have the body mass to sustain longer periods of starvation brought about by the drought. Or are the fittest fish those that are more resistant to the effects of this hormone? Or both? The end result might be that the largest fish would get the bulk of the total food available and therfore would have the advantage of surviving. However what about the small guys? They need less food to survive so they might be better off?  But then they would be subject to predation, being slower and weaker just by their small size. Bottom line, there must have been an evoloutionary advantage for this hormone to develop.

So, assuming this GIH does exist, then throw this wild scene into an isolated tank system with zero predation limited by the frequency of water changes. Rememebr homones are very powerful things. It is unlikely IMO that we could ever do enough water changes to eliminate its effect. It is too powerful. So then, why does it appear that same sized fish seem to fluorish in growth. Or is there another factor. Or several factors combined. Probably the later.

It would be interesting to do an experiment where a group of same size fish were housed with one or two smaller fish and see how the growth rate was affected of the larger fish. Compare that with the same sized group but this time with no other smaller fish and see how the growth compares. Then you could have another set of tests where a group of fish is housed with a couple of larger fish and see which was worse off. Group of small fish, or the larger minority fish.

Dave has a great point too. How small is too small? Is the growth affected by fish that are only 1/2 " different in size, 1" , 3/4 inch?

As hobbiests, we seek to provide the best possible environment for our fishies. Clearly water changes and great food is a factor. We are all limited by our relatively few tanks and too many fish! Should we start raising each fish alone to achieve its greatest potential? That would be sad to say the least. whatever works works. The cause is secondary, but it is fun to ponder the possibiities.

Do I believe there is a GIH? I'll answer that with another question. Do I beleive there is other intelligent life in this universe? Has it been proven that there is? Or isn't? Actually I believe, whole heartedly that there is IN FACT other intelligent life in this universe, far superior to our own. We have all seen them. I have examples right next to me. They go by the name of discus. Seems they've outsmarted all of us into spending way too much time on them. I actually think I see my guys laughing at me right now! :)

Dan

[brewmaster15]

Keep it coming guys- valid  points all.  

   I have another observation to add here   I have a tank of fine line Blue snake skins. When I got them they were all about the same 2 inch size. They now range from  3.5 to 5 inches..Thats a big spread.

Switch over  to a tank of a wild green X blue snake skin  cross I have . They are all growing at about the same rate. I culled when they were small at about 2 inches. they are now 3-4inches. All very uniform in size ~15 each per 75 gal tank(2 tanks), 30 %water change/day.

   This makes me wonder if the size differences seen might not be  based on genetics. I think most will agree the more inbred the fish, the weaker the genes  become., which is why  you out cross to bring in new  genes. Genes govern  hormone secretion internally, including growth  hormones.

  What do you all see when you breed  the wilds or wildXdom crosses?

  Again,  I'm not saying yeah or nay here, just offering ideas.
take care,
al

[DarkDiscus]

Al,

But genetics does not explain why you can sometimes take one of those smaller fish and separate him from the bigger guys and then grow him up to just as big as they end up.

There is definitely something environmental that causes this phenomenon.

The question is:  Wouldn't someone with a chemistry background have tested the water to see if this is the case?  I'm sure someone could test the water, determine all the hormones, etc and then try them each with the discus and see if they grow poorly in the presence of said hormones.

John

[daninthesand]

Al.

I see your point about the wilds. I'm glad you have experience with this. I was sort of trying to make the same point in my last post on this. I doubt very much if this phenomenon exists in the wild. Not simply due to the unlikely equivalent living arrangements we subject our captive discus to, but that it simply could not happen because of the wild genetics.

You have noticed a difference in the growth disparity in wilds vs. domestic. It would be a fantastic experiment to somehow get a hold of a wild caught batch of baby discus and see if this phenomenon could be reproduced with them too. My guess would be no. I suppose your expereince with an F1 batch of captive bred wilds would be the same thing.

It would be great to hear form some "old timers" ( No disrespect intended!) if they have noticed any difference in this phenomenon in the last say 40 years since domestic discus have become prevalent compared to the good old days when discus were real men. I mean real FISH!

Dan

[daninthesand]

John, I think what Al is referring to is a genetic *predisposition to the GIH having more influence on growth rates in inbred fish (domestic), compared to the wild variety. Sure, other genetic factors will affect growth too, and these can become more prevalent in inbred fish.

In wild fish does it hold true that if you seperate a smaller fish from it's larger counterparts, does it get a growth spurt? If so is it as pronunced as in domestics?

Dan

[DarkDiscus]

Dan (& Al),

Interesting.  I would tend to think the other way - as in since wild fish are less used to this hormone it would affect them more in captivity, but it's worthy of an experiment.

John

[Francisco_Borrero]

Thanks everybody for a most interesting and useful thread. I am not a discus breeder and thus can not offer direct discus evidence, but would like to offer some ideas. These come from my background as a biologist, specifically a physiological ecologist, and as someone who has worked rather extensively applying physiological concepts to commercial production of marine shellfish in aquaculture settings.
1) I believe it is quite possible that a GIH (or substance) may play a role in the growth differences/stunting of young discus. Very similar situations are well known and documented (down to isolation of substances) in plants, microorganisms, sponges and cnidarians (soft and hard corals and anemones).
2) I believe it is very unlikely that a a GIH-like substance by itself cause the growh differences, due to several reasons. First, it would not "target" individual fish, but affect all. Second, it is not necessary that a GIH-like substance exists at all: stress due to space/food/dominance competition is enough to result in growth differences. This is even when there is no direct contact between the large and the small fish. The very perception (substance in water or air) saying "I am here, you are little and I am big" has been found to affect a suit of animals, ranging from wolves, to cattle, to social animals, to plants. No thyroid-like secretion is needed. Call it psychological overpowering if you wish... Third, if smaller fish are under some sort of stress, growth will be affected anyway (even stress as that suggested above), whether or not there is some GIH-like substance present. This is not to suggest that there is no such thing as GIH. Personally I think there could be, just that it is probably not the only reason for growth differences in groups of young fish.
3) The idea has been advanced that GIH-like substances are unlikely because they would not work in the wild due to constant and major dilution. The best evidence *(in my mind) that they are not the only or even the major reason for growth differences is the very fact that THEY DO ACT IN THE WILD, and not only in discus. This is a reason "supermales" and "alpha/beta females" are found in natural wild populations of many cichlids, serranids, snappers, clownfish and other organisms. Once the largest one is removed, another will take its place and will henceforth grow big quickly and harrass everybody else and stablish his/her dominance to the detriment of subservient conspecifics.
4) In the aquaculture of oysters and clams it is a well known fact that having animals of different sizes together results in lesser growth, lower production and lesser quality. Very frequently, mesh trays (8 in a vertical stack) hold several thousand oysters each. Unless you grade by size at about biweekly or monthly intervals (depending on location and season), you will end up with a situation not unlike that of the discus batches. Grade by size regularly and even if you have trays with small oysters inmediately above, below, or to the side of those with larger oysters, your growth will be better, more uniform, and the product will sell better. Dilution in the water ??...unlikely.
6) Antagonistic effects of conspecifics on growth and survival have been very well documented among corals (hard and soft) and among sponges. In most cases and while specific substances have been isolated and proven to affect growth/survival, most of the effects have been attributed to physical contact or lack thereof. Some species even have long sweeping tentacles that extend at will and well beyond the physical location of the colony. By the way, these antagonistic behaviors are both intra- and interspecific. Thus, they affect any competitors from either the same or different species.
5) Picture the lawn in your front yard. If you don't mowe it often, you will end up with thin, skinny and long loose strands. There will be shading and dying of younger/shorter strands and these will the overshadowed to their eventual dissapearance. Mow the lawn more frequently and it will ticken and produce more uniform and higher quality yields.

I hope I have not bored you with this dissertation. I was just trying to put together my own thoughts on the matter and I guess I made you suffer through it. I apologize if this is boring to you or uninteresting.

Back to reality, I am seriously considering splitting the 10 wild fish I have in a 125gal. There are 4 fish that started smaller and just don't seem to catch up no matter how long or how many water changes. They eat just fine. Would they do better if they were in a group of similarly-sized animals ? From my arguments above you would think that I don't think so. Well, I do think so, but not necessarily because of GIH-like substances alone.
Cheers, Francisco.

[daninthesand]

Hi Francisco.

Not boring at all. It is refreshing to hear from someone else with some firsthand knowledge of the effect of GIH. It is interesting about the shellfish being "graded" by size and being raised together to produce max. growth yields.

Dale Jordan once told me that was how he raised his discus. He used to do exactly as you described. In a batch of growing fish, when he'd notice any that were either larger or smaller than the major group he'd move the fish to a tank with similar sized fish. He did this on a regular basis and found the fish overall did better. He had less runts.

Unfortunately most of us hobbiests don't have the luxury of so many tanks, but it would be useful to at least do the best we can by seperating our fish into similiar sizes, once they were done quarantine. I plan to do this as best I can now that I have a few more tanks. But when (and if) I start breeding and raising fry this might get pretty cumbersome. I guess I WILL have to convert that laundry room to another fish room after all.;D

Now, all I have to do is convince my wife! :o

Sheesh! :P

Dan

[gump]

Hi Dan & Francisco & all...
Very interesting, not boring at all.  I was thinking along the same lines and moving my smaller ones to a different tank.  Seeing I'm just starting out with discus, I only have the few and don't want to put less than 8 together (just babies yet). However, I do find that they do put on growth spurts a different times. The smaller ones have just recently put on a bit of a growth spurt, although still very noticably smaller. It's a hard call... by the time I get more fish through quarintine these smaller ones that I have now will be way to big to put with the new ones??? Or should one just raise 3  or 4 fish together..  They seem happy as a group...Aghhh
Pierre
ps.. Hope that makes sense to you!!! LOL

[brewmaster15]

Hi Francisco,
* Your experiences and input *here are not boring, quite to the contrary, they add *greatly *to our discussion. ;D

One thing you mentioned doesn't fit too well from a biochemical point of view though...

"The idea has been advanced that GIH-like substances are unlikely because they would not work in the wild due to constant and major dilution. The best evidence *(in my mind) that they are not the only or even the major reason for growth differences is the very fact that THEY DO ACT IN THE WILD, and not only in discus. This is a reason "supermales" and "alpha/beta females" are found in natural wild populations of many cichlids, serranids, snappers, clownfish and other organisms. Once the largest one is removed, another will take its place and will henceforth grow big quickly and harrass everybody else and stablish his/her dominance to the detriment of subservient conspecifics. "...
* ..
Where this is *possible, it isn't the only explaination.
This doesn't necessarily mean an externally secreted hormone is at work. *For example *in bird populations *if you remove the dominent *alpha male *red wing black bird, another will take its place simply because * the slot is availible. * A *hunter takes out the head wolf *in *the pack , and the wolf is replaced by a complex *social system's acceptance of the *new alpha male.

I would guess my problem with it occurring in the wild is how effective would be if a growth inhibitor were shed into a river of moving water. Would all fish down stream be more inhibited?

And then the only the other probelm is there would have to be *another hormone elevated in the fish to cancel out the inhibitor, and allow *for growth


*In many cases in the plant communities, it is not a hormone that *that is secreted *to inhibit plants of the same *or different species- its a toxic chemical. This is called Allelopathy.

*Perhaps a similar thing occurs in our tanks, just from the byproducts of having so many fish in so small an area. Suppose again *that *the larger fish tolerates this chemical better and *grows better...... just another *possibility.

There *is an inherent flaw in all of thinking here. To say that *something *like an inhibiting hormone occurs *because we see the end product is guesswork. There are many possiblities to explain what has been discussed. I think we have all touched on a few of them. *

Does any one know of a case *where this hormone has been shown in fish? *I think the most likely place *to look for info on *it would be *to *check into commercial Hatcheries *of fish like Salmon, Trout, catfish. Where there is money involved, there is a wealth *of research protecting it and promoting it.

One last *thought for all. In cases where you have seen Discus grow larger than their siblings *and *"inhibit them" do you know if it was a male *or female. ? *My reason for asking this is Females become sexually mature sooner than males, and estrogen *compunds *, both natural, and man made *have been *shown to affect *the sexual developement of fish . Sexual developement *triggers a cascade *of other hormones involved in growth (think testosterone and muscle *development)

*take care, al

[John_Nicholson]

I am at work and so did not take the time to read every line of this thread (although I find it very interesting) so if this has already been cussed and discussed please forgive me.  I don't think it is one hormone but possible a combination of several hormones.  As people age and grow our hormone mix changes.  I assume that it happens this way in other species also.  Fish that are at the same point (size) on the timeline are all producing the same hormone mix and so are unaffected.  However fish that are behind on the timeline (a different hormone mix) are stunted.  Think what would happen if you gave a child adult hormone treatment.  No telling what would hwppen.

-john

[ICL]

Forgive me for not being very open-minded, but like I tell AT&T when they call: "I'm not buyin' it." I realize just about everybody on this site has more experience with discus than I do, but I'm no novice to keeping other fish and I find it hard to believe that this "hormone" would exist with discus but not with other fish. Your observations about the growth rates of differently sized discus in the same tank I'm sure are accurate. But to attribute that to a "growth inhibiting homone" is a bit of a stretch in my opinion. There must be fifty more logical reasons for this to happen. When you have a litter of puppies, there are just "alphas" among them and these will be dominant in every way. They will also often grow larger and thicker than their siblings. They are not releasing any growth inhibiting hormones as far as I can see. If I were shown proof, I would obviously change my mind. But it sounds like these experiments so far are only confirming your observations, not the cause. If you could isolate the hormone you think is there and establish how it works in a "scientific" way then I would buy into it, but until then I'm afraid it sounds too far fetched for me. I don't intend to offend anybody, this is simply my opinion. And you know what they say about opinions...

Ian

[JacKWattleyDiscus]

Ian
Your opinion also counts, but I think your missing the point about this phenomenon called GIH for lack of a better name. I would hate for any hobbyists to spend good money on their discus and stunt them because no one warned them. Be it GIH or little green men from Mars the events are occurring even as we speak.
Knowledge is power. By hobbyists being aware of these occurrences maybe they can avoid them and enjoy full grown discus. I know I would want to get my monies worth out of my fish.
Gabe
PS
I too do not buy into ATT.

[ICL]

Gabe, I am all for sharing your experiences with new hobbyists. It is good to know that smaller discus do not grow to their full potential when kept with larger discus. I'm glad that I am able to learn from you based on your experience. But that is just what it is. Experience with discus not growing as large when they are kept with larger discus. This is valid observation and I believe it is accurate. However, I just don't see how you go from that observation to suggesting there is a specific growth inhibiting hormone. It is a huge leap with no scientific evidence to back it up. I can't disprove it, but because nobody has ever proven it I will withhold my support for this hypothesis. If or when it is proven, I'll be the first to say my opinion was wrong. After all, my opinion, like yours, has no scientific evidence to back it up. I respect that you want hobbyists to grow their discus up big, I just don't think that the cause you are using to explain this effect is accurate. In the end if we both believe that larger discus will inhibit the growth of younger discus regardless of the cause, then we can both raise nice large discus :)

Ian

[JacKWattleyDiscus]

Ian here! here! to larger discus :thumbsup:
On this we both agree.
Gabe ;D

[ICL]

Yes indeed! ;)

[Lynn]

Hi Everyone,

I was just reading everything in this thread and a thought popped in to my mind :crazy:
If you think about what happens in the wild with rainy and dry seasons then the possibility of this GIH is there.
Okay...it rains alot, lots of room to swim lots of fresh water/food. When the rain stops and things dry up fish are trapped in pockets along the river bed. If everyone keeps growing then pretty soon there is no room/food and way too much waste. There is usually a dominant fish, if they die another moves in. This happens with many species. Maybe being in a confined space like a tank, even with the best TLC, will spark this GIH phenomenon. Just an idea to ponder.
It sure is fun to share ideas with you guys! ;D
Thanks for the great thread!
Lynn

[Denny]

i have an observation unrelated to discus but related to the subject.  we have a relative that has a cabin on a tiny lake that has little fishing pressure anymore. ten years ago the pressure was greater(more fish taken) and it was not unusual to catch a 5-7lb fish. now no one fishes there but my brother inlaw and me twice a year.  the fish are very abundant as you can easily catch and release 10 fish in an hour but they are all under 3 lbs. a dnr person up there told me that the fish release a hormone that builds up in smaller lakes and controls the growth of the fish so that they don't overcrowd it and run out of food. they all release the hormone and it becomes a cumulative effect that as the number of fish increase, the concentration increases and that dictates growth potential. this has also happened in an area lake where the bullhead population got out of control and all of a sudden there were millions of tiny fish and no big ones like there were before they used to have. and the dnr netted the lake and found indeed that the fish were stunted and that it was attributed to overpopulation.

now take into account you put 6 fish in 55 gallons of water. never in nature do you find this density. a 50% w.c daily is a drop in the bucket to the turnover of water in nature. you would need to continuously change the water over many times daily to say that w.c don't effect gih as it is a closed environment.

and last but not least, myself and 2 friends in high school each bought one single pihrana. i had a 10 g, one had a 20 g and the other had a 35 g. we did similar maintenance and the results were mine was the smallest,, the 20 g next and the 35g was by far the largest. and the differences were dramatic.

so in conclusion i agree with gabe on this with the addition that tanks are a closed environment and the size tank and changeover in water supply all have an impact.  

[Denny]

i apologize for sending this twice :-[ :-[ :-[ :-[

[Willie]

Francisco's contribution is most useful, since he cites scientific evidence.  Note that growth inhibition occurs, it is restricted to organisms which cannot move, e.g. plants, coral, etc.  Therefore, the production of a chemical to inhibit competitive growth nearby would confer an evolutionary advantage.  There is no advantage for fish to do this, except for those that evolve in aquariums!

[Denny]

there is an advantage to gih, in that if there are no natural enemies, the fish would overpopulate the lake and when they outpaced the food supply they would starve and die off,  by limiting growth as the population rises, they limit the amount of food each fish needs and thus helps to keep the ecosystem more balanced.

[JacKWattleyDiscus]

Today after work at the hatchery I went up to visit Wattley at his home in Ft. Lauderdale.
After a lenghthy conversation with him about the engagements he has up and coming, I brought up this thread. The next thing I knew we were walking into the frog room. For those that don't know, besides discus one of Jack's many passions is poison arrow frogs.
He showed me some petri dishes were he raises the tadpoles. In two the same exact ocurrance was taking place. He placed two larger tadpoles each with two smaller. The larger doubled in size while the 4 smaller in the two seperate dishes lagged behind. Add frogs to the list of growth inhibited by larger individuals.
For what it's worth!
Gabe

Gabe,
    That is very interesting.
Miles

Wow! what a topic
Good Job Gabe on the post busters of the year award
hee.hee.hee JK.
The topic is very interesting indeed!
But still I think Size would Matter as far as compitition for food and neutrtion! If each were scarce. But like I said in another post when raiseing discus in this way with large amounts of food + water I have never noticed
it when sizes were mixed. Now off topic a bit. I do know females will release pharmones into the water triggering other females to spawn. So I would think its good ideal to put breeders on a central filter system but never fry what a mess. JMO!
Now! with this my friends I leave you in mind a little old poem that comes to mind LMAO! ;D ;D

Mr Discus!
What big Eyes you Have (THE BETTER TO SEE YOU WITH)
little BLKworm
Mr Discus!
What a big Nose You Have (THE BETTER TO SMELL YOU WITH)
little BLKworm
Mr Discus!
what big ears you have (THE BETTER TO HEAR YOU WITH)
little BLKworm
Mr Discus!
what a big mouth you have ( THE BETTER TO EAT YOU WITH and More!!!!!!!!!little BLKworm

Ok sorry I thought it was Funny at the Time!  :-/
ha' ha' funny
TakeCare + Goodnight
Cary Gld!

[April]

LOL Cary. sure ......its great. kinda reminds me or the big bad ruff as my kids used to call it.
heres my poem i taught my kids as soon as they could speak

fishy fishy in the brook
daddy caught it with a hook
mommy cooked it in a pan
baby ate it like a man.

I f you teach your little Jack....not Jack Wattley......he may decide to go fishing in your tanks and throw one in a pan. they fit well in a frying pan. nice and round.
my one tank is right by the stove. if they jump out they'd literally go from the tank into the pot.

[jim_shedden]

A SIDE NOTE : I have had a minor water problem (acid, soft and no KH) and my 16 year old daughter took the string to Laurention University to a chemistry proff. He was blown away by the knowledge that was there (but could not help me). Then my daughter took this thread over to him. He was so impessed that he called me for more information. I advised him that if he wants to learn more he should read "SIMPLYDISCUS.COM". I find it amazing that as hobbiest and some full time breeders we have this wealth of information. It is fantastic. As for the thread.........I am simply blown away. Thankyou. Bye the way : Dr. Stephenson........welcome.

Jim

[JacKWattleyDiscus]

You know, maybe I can contact Dr. Ruth Francis-Floyd at the University of Florida. I'am pretty sure that extensive experiments have been conducted on Telapia, Salmon, and channels cats. Maybe the food industry where the big bucks for research go, can shed some light on the scientific specifics which we are experiencing.
Gabe

[JacKWattleyDiscus]

You know talking about hormones and pheromones.
8 years ago it was discovered that the African rhino numbers were dwindling. A research team from the National Geographic Society was sent down to investigate and document the situation.
It was discovered that the females were not producing enough pheromones and therefore were not attracting the male rhino's. In an effort to help the rhino's to reproduce, they hired a fashion consultant from Victoria's Secret ::)
After a 5 year study and 5 million in expenses the following was the cure for the rhino pheromone deficiency. :o

[JacKWattleyDiscus]

And I bet you thought we did'nt have a sense of humor.
;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D

http://www.skepticalaquarist.com/fishes.html#fishmisc

(page down toward the bottom...Misc...then GIH)


Sent to me via email by a discus keeper on another forum.

Mat

Space, food, and mates for the passing of one's own genes are competed for in nature by all species making GIH a useful tactic in evolution not only by non-motile species as corals and oysters, but all creatures in a given enviroment. Why would this be an advantage only to a non-motile species?

The example of the growth of grass is not valid in this topic because the cause is not caused by a chemical excreted by competing grass, rather the cause is due to competition of the grass's energy source, light. This is why we can't compare the growth difference in a given spawn because we are not talking the same effect and does not relate to this topic.

LMAO!! Gabe....where'd you get the picture of my ex-wife?? :o

Tony

[JacKWattleyDiscus]

Larry, my hat is off to you. It's people like you who will one day find the true answers. Keep up the good work.
If I find anything from my end I too will share.
Gabe

[Ryan]

:spit: :funny: :spit: Gabe, that was a hilarious picture... and Tony, the ex comment was just over the top! Thanks for the laugh! It's an interesting topic, but I wasn't expecting those two posts AT ALL... hahaha..

Ryan

[April]

LOL Tony!!  ;D
shall i send her the link?
what was that email addy again? think Ed knows.........
;D :o
didnt they bond via email?

Hey Prilly

LMAO AGAIN!! ;D Uhhh I forgot about that ;D
Bond.....ya....thats one way to put it ;D ;D

Tony :bandana:

[Carol_Roberts]

For those that got lost scrolling thru the Sceptical Aquarist site Mat posted, here is the info:

Growth-repressing hormones.  Nernst posted at AC, Nov. 2000:  "The growth-inhibiting “hormones” whose levels could be lowered with water changes are, in diminishing order of importance: Somatostatin, Norepinephrine, Serotonin, Nitric Oxide. Thyroid-releasing hormone and thyronines haven’t been proven to have a direct relation; neither have estrogens/testosterones. There are of course other non-chemical things that affect growth, like stocking density and “social interactions” among fish."  He gave the following references to publications:


Peng Chun and Richard E. Peter, "Neuroendocrine regulation of growth hormone secretion and growth in fish."Zoological Studies. 36(2). 1997. 79-89.

Aubrey D. Uretsky and John P Chang. "Evidence that nitric oxide is involved in the regulation of growth hormone secretion in goldfish." GeneralComparative Endocrinology. 118(3). June, 2000. 461-470.

Hans A. Hofmann and Russell D Fernald. "Social status controls somatostatin neuron size and growth. Journal of Neuroscience. 20(12). June 15, 2000. 4740-4744.

Sameer R Phale."The neuroendocrine secretion regulates growth hormone release in teleost fish" Fishery Technology. 35(1). Jan., 1998. 1-8.

H. Martin Oyama, E J. Sussman, K. Weir G C. and A.Permutt ."The biological activity of catfish pancreatic somatostatin."Regulatory Peptides.1 (6). 1981. 387-396. This article shows how Somatostatin could be freely secreted via the gut into the surroundings.

I know we have several hobbiests with a scientific background, maybe one of you would be interested in pursuing this. . .
Carol :heart1:

Although there was no explanation on the "how" of GIH in fish, at least the link tells us there is such hormone as GIH. All I know about Somatostatin is that it is a pancreatic hormone that effects insulin and carbohydtate metabolism in humans. I'm sure it is similar in fish, but do not know if this is the hormone that Jack Wattley is refering to in his theory. There are other hormones that inhibit growth.

Mat

Hi all,

Growth inhibiting hormone or growth inhibiting factor(s)

Having read all these replies in here and on the simplediscus forum.  I find this is very interesting and a lot of good ideas have been put in


A pheonome is observated by some breeders (Gabes, Mr Wattley, I respect him for his contributions to discus keeping) that  growth is inhibited among smaller sized discus when keep with large ones
.

To conduct a proper scientific experiment, it must have the
4 Ws (who(discus), where(in a closed small space), when(growthing phase?) and what(retarded growth) in mind and statistical analysis tools, too.

I drawn up part of the list here.


In other word need to design an epidemological experiment to address the question!  


Statistical power analysis (What is the minimum difference are you going to detect? ie define what is stunt and what is normal, said 10% or 20 % between growth within a given time period.,  

Confounders(factors either positively and negatively associated with the outcome (growth), ie ph, food mass, water temperature, number of hours receiving light(some hormone are regulated by light, as well many other parameters  normally associated with discus keeping.)
Bacteria count, No3, No2, NH4+ ion, ca etc

Controls both positive and negative controls are needed,
a species closely related with discus (the angels) and  some other species are needed. And you do whatever you do to the discus you do it to the controls fish.

samples size : Pool discus from different parent lines together and randomly assign them to experiment group by permutation based on body size. (at least 40 per experiment arm)  

The technician who carrying out such experiment should be blinded for what the outcomes are.  

The experiment needed to be repeated at least 3 times to  re-check the results.  

Record both individual mass and group  mass at the end of the period. calculate the growth rate and adjusted for the parameters that I mentioned before!  

Carry out statistically analysis accordingly, start with a summary statistics, then p-values, correlations and Analysis of covarients.

I will only call an experiment is conducted scientifically if it contains all the about ingradients.


Why should one jump into conclusion a hormone is involved? We have keep our mind open,  a or some factors might be there in inhibiting growth. I would call it GIF for Growth inhibitatory factor. Even stress can be a deadly factor!  

Please, in the history of scientific research, we often have the solution to the problems hundred of years before the mechanism is found.  

John Snow, an Englishman did not know a bacteria was involved with cholera in London during the 18 AD. But he stopped the spread by turn off the water pump!  

Lewis Paster he never saw a virus under microscopic, but he known some "agent" was  there.

Solution to stop small pox was conducted by a young English countary doctor's (George ?) careful observation that milk lady who had cow pox did not get or get small pox and recovered from it.  The mechanism only worked out during the last 30 or 40 years!

Therefore, the mechanism is not as importent as the solution. If by change water and sorting out size can increase yield ! I am sure a lot of breeder would not mind to do it.  

While, sorry for taken you so long to read this! It take me sometimes to make my decision to post this! Hope this is not going to offend any one!  

Some hormone find clown fish is so powerful that can trun a male into female and vise versa.

Thank you for you attention!

Martin  

[DarkDiscus]

Great thread,

Humor, great discussion and everybody enjoying the debate.

John

[brewmaster15]

Hi Martin,
 Those are valid points, and I believe That Gabe and others here who feel this is going on, are using the term hormone  loosely. Growth Inhibiting Factor, would be a more  open ended description.
 This is a great  topic, and  I have an idea  for an experiment that may answer it.  If someone like Gabe was to take one of his  grow out tanks that had one of these larger fisher (  the inhibitor fish), Remove  all the other fry. Artificially rear a set  of Fry. Split the group into 3 group.  One set of fry gets water  from a tank  containing  the group of  fish you moved (the inhibited ones),. One set gets  water  from the inhibitor fish tank.   The  third group is your control, it  is raised with clean   water.
  An N= 35-50 per group, will give  you plenty of fish to obtain statistical  significance.  
   One would expect that an inhibitor strong enough  to inhibit the growth  of the fry , would have a dramatic effect  on the most  developmentally active  stage  of the fry, the first several weeks.
 Hth,
al

Ps there is another phenomenone here to consider.There is a branch of biology that studies population dynamics and densities. In many animals  as the numbers increase stress( a measured  parameter) increases.We know for a fact the adverse reaction stress has on discus.   Keep in mind that the Inhibitor may not be secreted into the water, but may be made internally  by fish  in response the population dynamic. This would help explain why one fish doesn't secret something that inhibits all other  fish in a tank equally ( a hormone  most likely would) differnent fish would deal with the population dynamics differently and so the growth may vary, if the stress affects the hormones inside  the fish. In many ways stress it self is a hormonal based  response.

[Carol_Roberts]

Great post Martin!

Now we can all see how much work would be involved in conducting a bonafide test for GIF.

Your response was very practical.
Therefore, the mechanism is not as importent as the solution. If by change water and sorting out size can increase yield ! I am sure a lot of breeder would not mind to do it. *

Does it matter what substance stunts the fish as long as stocking by size and adequate water changes can prevent it?

CArol :heart1:

[brewmaster15]

Hi Carol,
*technically no , it doesn't . But many are driven by the need *to understand the reason why something occurs. Usully they are scientists *or people who are scientists *without knowing it :)

Realistically *though,you need to understand a probelm *before *you can solve it. Superficially water chnages and moving fish may *appear to solve the problem, But does it? For example, perhapd it is a hormonal inhibitor... Does this hormone *interfer with *the *development of the sexual organs of the *fish as well as its size? (My guess since they are linked would be yes) *Does this maybe explain *male fish *that seem to do a poor *job *at fertilizing eggs ( were they inhibited *as fry?) * Questions like this need to be answered for our understanding of the hobby to go *forward--at least *in my mind they *do, but i have been told I am obsessive *compulsive *;)

Take Care,
al

Martin's post is accurate regarding the determination of this substance. To be considered valid, scientific method needs to be followed to be accepted amongst the scientific community. The problem here for me is, as well as most on the forums, is that I have neither the space nor the time to carry out an experiment such as this. I have to rely on what other's have done in this area who are more knowledgable and have more experience than I do.

There could already be information out here that would settle this discussion, but I don't know where it may be. Probabally at some university lab sitting in a folder.

Mat

[brewmaster15]

We'll find it Mat,
* *I think the sum of the experiences on this board and others probelms exceeds all the questions *out there. The probelm is assembling the puzzle...but its also what makes the hobby so interesting :)

* Keep *asking questions. By asking and posting you bring it to forefront *of cluttered *minds like mine, now I'll keep my eyes out for Info on Growth inhibitors and fish. I'm sure the others that posted on this thread, or read *it will also.
*Maybe one of our breeders willtry some experiments, if you(the breeders ) *do and want some help setting up the design , let me know, I do this everyday :'(

Take care,
al

Hi again all,

al, it is well known that rabbit in wild follow a 7 years population cycle, once the pop., gets too high the bunnies just drop dead due to heart attack. One species of seagull need a meter square before display breeding countship, kango will delay or terminate the growth of the fetus if there is not food around. As in man we have the Type A male!

Seeing two large frogs growth bigger then the smaller one is not good evidence, because they are not at the same growthing phase.

As for the design of the experiment, cross over design and also  2 or 10 dilutions with your "inhibatory" agent is needed, add those.

Hormonal effect, by defination a hormone is a substance that can bring about the physiological chages within cell or organism. It be of protein, IL1, IL6, TGF(tranform growing factor), vitamin D. Calitionon, Calcium ion, PG2, etc. All are cytokines that may play a role in cell growth.

Wanna to test them all? ELISA, HPLC or ratio labelled antibodies vs serum and tank tank water. How much money do  we have, and time?


Dougall, in here I am pointing out one of  the methodology tool for a  cross sectional study as as well for a longitual study with crossing over design.  
We use the good old tool everyday,  during the 80s, 3 isolated cases for rare skin cancer were find in LA., under carefull observation. Later the disease was identified and the mechanism worked out and it was due to a virus later  HIV ! Do I need to say more on the name of this disease?

I Guess you are looking for something fancy mechanism just like me! Would like to know the true, and the bottom line.

To determine the mode of action of a given substance, the tools freqently applied are ELISA, HPLC, sectioning of the tissue with up take of ratiolabelled ligand to the  receptor.

The section is then exposed in X-ray film and the position of the location  may shown. Wanna do a receptor - hormone radio binding assay?

The technical aspects are huge you need, statistican, epidemologist, biochemists, immunologies, etc.

Those techniques are for substances already known to us, but substance X, you need to isolate the protein, purified it and give it to fish and see if you can induce retard growth in the optimum condition! Then, here comes the protein sequencing, and DNA sequecing with the insight for similar   sustance find elsewhere!  

20 % of the river water that go to the sea is from The Amazon. Can a hormone work in this system? I do not have the answer.  

Are we ready or willing to dig a bunny hole for this mechanism of action? How deep is this bunny hole? This project would certain gain you more than a Phd!

Do I belive in GIH? Seeing is believing! I need proper evidences for the acton of GIH, its structure and mode of action!!  

I thing both stress and the growth follows the normal distributions curve(from my very first post at simple discus) may be one of the answer!

Yes, again this is a rather long reply!

Wow! GIH is stressful, it is even worst when you are close to 40!!!

Thanks for your attentions
Love me, love my fish!

PS: I also post this at Jedd's forum, just like the other one!

I tried to read the thread(lurk) at big heads....This whole topic is way out of my league but very interesting....Unfortunately you have to join and be protected from mass spam attacks to get any info there....too bad :-/

Tony

[brewmaster15]

Hello Martin,
  What  is  you back ground? You are very knowledgeable about analystic techniques.
  A  thought on some of your methods though,
my design   for an experiment  is the simplest to test  if there  is  something   that may be going on.  Techically the methods you suggest are great but we  do not have  information to use them  yet( I have the  tools   where  I work to do so)

Elisa... You need  an antibody  to what you are looking for, unfortunately  we don't even know what that is, if it is.

Hplc... Chromotography relies on  Peak elutions, again it only works when when you know what it is you are identifying.You may be able to take a water sample  and find a peak and make and educated guess, collect that chemical, and analize it  by Gas mass spec... Its a lot of work for such a  diluted  substance.
 
In my lab we always start with the simplest  experiment taht answers a question, then re-design  another experiment  to add additional understanding.  Information comes step by step.  You are correct in your portrayal  of how difficult it  is  to do though,
  but here in lies the joy of science, does it not? ;D

take care,
and  thank you for the ideas....

-al

[daninthesand]

Hi gang.

I was thinking... (oh oh!)

We have all seen the effects of (lets label it for now) GIH. That is, stunted fish that never seem to reach the size of their siblings, until moved into a tank with more "like-sized" fish. Assuming of course it is not otherwise genetically stunted. (and how do you prove that!)

My question is does anyone have experience with the time frame on when reduced growth due to the effects of having larger fish in the same tank is irreversible?

My thought is that if you catch it soon enough (whenever that is) you can still grow out the smaller fish with good results to match the growth of his/her larger siblings (by larger I mean faster growing).

It would be interestng to know whether this hormone only affects fish up to a certain maturity (regardless of size) or whether it is size dependent. Sure you can argue that all the fish of the same spawn should be maturing at the same time, but this is not necessarily the case. (Let me make clear that my itention for using "maturity" *is to imply some sort of point in the fishes life when she develops this immunity)

Potetntially all discus of all sizes have the ability to be "immune" to this hormone. Is this immunity based on a more mature fish having the abiltiy to somehow block this homonal effect, by developing some type of system to prevent its effect as he gets older (maturity)?

Or does the mere mass of the fish dictate how much he can combat this phenomenon. I'm thinking here of a system already in place for all sizes and ages of fish, whose degree of functionality (the ability to combat the "homone") depends solely on his size. Maybe its a an organ or gill size issue. The larger the fish, the larger the gill surface area or organ size, and hence the less effect of this GIH?

Just my 3 cents...

Dan

Here's a story for ya dan.  My first batch of fish was 7 little guys from Universal.  I had one fish that didn't seem to eat and faced the back of the tank a lot, always hung out on its own.  After a couple of months I finally saw some white feces (tough to do when it's not eating).  I'll bet it had barely eaten in over a month.  It was small and pretty skinny.  Chalk it up to newbie concern but I didn't want to medicate until I knew what I was trying to cure.  So I popped the fish into a hospital tank and treated with metro for 4 days and then left the fish there for another week to regain its strength.  It was eating really well by the time I put it back in the main tank (my only other tank) but it was 1/2 the size of the rest of the fish, about 1.5" whereas the rest were 3".  I didn't think anything of it since I had no other alternative and didn't want to leave it on its own in the hospital tank.  Within about 2 months that fish caught up with the other fish and passed some of them.  It was a Super Red Royal Blue and in my experience they grow at a greater rate compared to other Discus (less inbreeding I imagine).  It was smaller than the other SRRB I had but larger than the RSG's in the tank.  In the end it jumped from the tank and croaked so I can't show you a picture of it today but it was one of the largest fish I had when it died (damnit all).  So apparently there was no GIH inhibiting that fish.  I think there are one helluva lot more going on in these glass cubes then we know and a lot more that affects the growth of our fish... genetics of the fish in question being one.

Dave

[daninthesand]

Hi Dave.

Great example!

Yes, I agree with you that there is definitely a lot more going on that affects fish growth and ultimately its max size. I think everyone would agree.

The more we know and can prove by way of example and repeated experimentation, or trial and error if you will, the better off this hobby will be.

I do worry sometimes though that someday this discus thing becomes almost too easy, and might make it all seem less challenging and less interesting. I'd hate to ever get bored with it and lose interest....

Dan

[brewmaster15]

Dan,
 I think we are safe   from that fate,  now Tyler and fishguy.... they may get bored if we find all the answers. somehow though, there are al;ways more than enough questions and angles, and opinions ;) which is why I love this  hobby so much!
take care,
al

Al,

Yes, I agree with what you have said about the testing. It would be hard (impossible really) to create an antibody to GIH, when we really don't know exactly what it is. Once it is isolated, then an antibody could be created and an ELISA test would be possible. This thread really shows how complicated the subject is.

Mat

[perche]

Cool thread !

Just to throw something in, research was done on the effects of pheromones on the health and growth of koi. This was once on Doc Johnson's website contributed by Chris Neaves.

For those interested, here's link here : http://www.sfbakc.org/koienews/hormones.html

ATB

perche,

Thanks for the post. It was interesting reading.

Mat

[bokgrasul]

Thank you for sharing your experience with us!
For me ,it really helps!
8)

[EthanCote.com]

Eeerrrrr it has been several months since this topic first came into light. Out of curiosity, has anyone try experimenting with their Discus to find out what the substance(s) in question is/are?

If someone indeed is running some sort of experiment on this topic, please share your finding when it comes to light.

Many thanks. It was indeed an interesting read, now I'll go take the 2 aspirines as the doc ordered. ;D


Cheers,

Chi.

[ronrca]

Wow! Info overload! Al, could you do an article or summary! This is cool stuff but only took me around 2 hours to read! The link though by perche I can not read because I do not have a password! >:(

[mrespo]

I would just like to add my spin on this topic. I'm not an expert on fish metabolism or biology, but I know a little about growth and hormones.

All living organisms, be it a fish or a person, are genetically programmed to grow. Also, the time frame for which this growth will happen is genetically determined. Growth hormone (GH) is released into the body and stimulated somatic growth. Following puberty, levels decrease and growth slows then finally ceases. This can vary greatly from one individual in a selected species to another. That is why, in part, we can have siblings of various heights and sizes. It is what accounts for variety in any given species.

Growth is also influenced by internal and external stresses placed on a given individual of a given species. If water conditions are poor or subject to extermes; if nutrition is inappropriate or inconsistent; if one individual is being picked on more than usual by other fish. All of these can influence the growth of a fish. And this is by no means an exhaustive listing.

In nursing, we have a phrase we apply to circumstances like this. Failure to thrive. You often see it, for example, in neonates who fail to form a bond with their mothers, for one reason or another. I believe this can also apply to fish. Stresses ranging from poor nutrition to social isolation will have an impact on how well that fish grows. Therefore, IMO, minimizing stresses the fish experiences with add to its potential for growth.

Since hormones such as GH and GIH are internal mechanisms of control, I'm somewhat skeptical about the ability of these substances to influence the growth of other tankmates. I'm not saying it doesn't happen, but the scientist part of me would like to see a study identifying their presence in the tank water at a sufficient enough concentration to exact an effect on others in the same tank. Along these same lines, it would seem that if every fish in the tank is excreting a growth inhibiting hormone into the water, eventually, the desired outcome would never be reached. That is, there would be such a high concentration of GIH that all of the fish in the tank would be stunted. But in reality, we know this is not the case. From the readings I have done, I have yet to see any solid proof of an organism being "immune" to a hormone. I tend to believe that once a certain age has been reached, organisms are genetically programmed to shut down their growth. Stem cells no longer function in the adult like they did in a juvenile. Mitosis slows or ceases in most organ systems. Hence, all the focus on stem cell research and attempts to "trick" the body back into a regenerative mode.

For these reasons, I adhere to the failure to thrive hypothesis. Minimizing stressors during the critical time frame when growth potential is optimal greatly increases the fishes chances of obtaining it's fullest potential. In short, the answer may not being flashy or techinically advanced. It is, in truth rather mudane: frequent water changes, good nutrition, and a stable environment. It may not be glamorous, but it is tried and true.

Anyway, that's my two bits. Thanks for listening. I'll get off my soap box now and go back to my desk.

I did a similar experiment/test to confirm the affect of GIH about 6 months ago. I did not care about the isolation, identification, or separation of such hormone. I just wanted to confirm the affect of this hypothesis.
What I did was to keep 2 fry with their parents for as long as possible. By doing so, if GIH indeed exist, these two little guys should be runts in no time. You agree?
Well, I separated these two youngster from their parents at 3 months (2.5 inchers). The result were very healthy fish. The best looking fish I had. They are now the same size as their sibblings.

This experiment also gave me great data on parental care, slime consumption, and breeder's health. But absolutely no trace of GIH; however I will continue to do this for each and every batch.

Maybe GIH is produced when the adult fish are in stress within a crowded environment of young fish? If this is the case, then my experient is not valid because the parent fish were not crowded of young fish. I will do this again with more than 2 young fish. Or maybe GIH will not be present within a family environment. Who knows?

[mrespo]

Your experiment does, in my estimation, lend credence to one thing: there is a high probability that GIH is not present to the water i.e., secreted by the fish. Again, my contention would be that if that were the case, the hormone would reach such a level as to feed back unto the adult fish that were releasing this substance. In short, all the fish in a closed environment would be stunted.

To rule out familiar variables, one could introduce fry from a different pair, or batch back into the parents tank. If they grow to normal size, then GIH is most likely not present and familiarity has little to do with it.

My original hypothesis is still that stunted fish result from environmental factors more so that GIH. GIH, in my understanding, is an internal hormone which regulates when growth in a fish, or other organism, is to be shut off.

An experiment I may try at some point would be to take a group of fry from the same batch and place them into their own tank. I would then manipulate their environment to present extremes to them. This would include all known variables such as temperature, water quality, amount and timing of food given, and so on. They would be measured at regualr intervals along with a control group comprised of the same amount of fry from the same batch who have not been subjected to these extremes. Overall growth rates as well as their final adult size would be compared to see what effect environment played in their growth.

A third group could also be analyzed. This group would be made up of fry from the same batch that were placed in a tank that would simulate overcrowding. If GIH were present, it would probably be seen in this group. All other variables would be the same as the other control with the exception of the overcrowding. If this group were stunted, then perhaps GIH may be playing some role. If there growth is comparable to the control, GIH is probably not a major factor.

Just a few ideas of future experiements I'd like to try in time.

Most runts that have developed in my tanks with larger fish around, did not exhibit normal behavior in eating or socializing. I suspect some illness was responsible, but nothing so obvious that it could be diagnosed. Possibly just plain old bad genes. "Piss Poor Protoplasm" is a phrase that is used behind the scenes
in the medical field occasionally and I suspect it could be applied to discus as well. There's just something, who knows what, that causes certain individuals to grow poorly and be succeptable to every little bug that comes along. These little guys rarely develop into the robust fish that swim to the front of the tank looking for food when approached, no matter what kind of intervention you try. Fish have endocrine systems like other organisms, and at least for me, these can be difficult problems to diagnose without doing extensive laboratory testing. These fish could be suffering from some endocrine problem causing a systemic "failure to thrive" picture as mentioned in another post. Growth hormone deficiencies, blood glucose problems, etc. Also, there are more blood disorders than you can count. Anemia in discus? Why not. When you think of all the things that can cause illness, only a fraction of the problems, with humans in mind, are caused by infectious agents or nutrition problems. At least for me, I tend to always think of an infectious agent when my fish have problems, mainly because that's something I can treat. Water quality and nutrition are the other things I can influence. But that's about it.
The "evil humors" theory in medicine was used to try and explain illness that was not understood. And of course now we know that most illness is caused by toads or small dwarf's living in the stomach. LOL...a Steve Martin line from a distant SNL. Anyway, I suspect the Growth Hormone Inhibitor theory is in the same vein.

[mrespo]

I agree, edibill. GIH is an endogenous factor influencing the individual and not the group. Poor immune systems, endocrine problems (Diabetes for example- why not in fish?), bad genes, and a host of other agents are most likely the cause. Even with optimal conditions, some fish will just not thrive. The best we as breeders and hobbists can do is to provide the very best of conditions for our little ones and let nature take it's course. If after this, some of the fish don't develop as we would expect, then at least we can say that we did all we could.

[Steve Rybicki]

This topic was linked to from the Angelfish Forum, so I thought I'd add my 2 cents.

I have raised many discus but I'm now doing mostly angelfish. For more than 20 years I've heard of growth inhibiting hormones, but have never seen where one has been identified in water inhabited by fish. That alone makes me skeptical, however my own experiences have convinced me that small fish have no disadvantage, just because they are smaller.

I have frequently taken small juveniles and put them in with pairs of discus and angelfish that have had aggression problems. I'm basically using these small fish as dither fish. Time and time again, these small fish grow at enormous rates and end up the largest and most dominant fish in the tank. I've seen juvenile males grow up and overtake the original male in a pair, and then become the mate for the female. In fact, I would go as far as saying that small fish in these situations, grow faster and are more vigorous than juveniles that are competing with each other. It is my contention that juveniles are more voracious feeders than adults and without the competition of other juveniles, they thrive and grow at very fast rates. In the past, I've used culls as dither fish, because I thought they would be killed or harassed until they were worthless. Now, I use my potentially best fish, because I've found they almost always end up the largest, best conditioned fish I have.

It is my belief that growth problems in a group of juveniles is the result of environment and/or genetics. I simply do not see any evidence of any growth inhibiting substance given off by larger fish.

[wildthing]

Oh-O!
Not this again....
:)

I can tell you this for sure...Jack Wattley NEVER NEVER said growth 'HORMONE'........ I have spoken directly with him about it & he gets quite upset ( actually, for Jack , he gets really quite angry about it) . He does not agree there is a hormone involved. If Gabe says otherwise he is misquoting Jack.Go ahead, ask Jack yourself. He will only acknowledege the possibility of a 'FACTOR'.
Terminology is very important.
I have also spoken to Professor Michael Mauel ( phd head of vet path dept a U. .Ga specializing in fish) & also to Professor Bob Goldstein ) phd parasitologist & famous aquarist author) on this subject last time it came up.
Both agree, there is (almost certainly) no HORMONE involved. It would make no evolutionary sense & have no practical value in the Amazon. It would be a waste of energy in the survival game . Discus have NO organ to produce such a hormone. No hormone has ever been found in Discus that would have this effect.
On the other hand even trace amounts of nitrates have been repeatedly shown to produce smaller fish. Hormones are removed by carbon & protein skimmers even in f/w & are easily destroyed by mild UV sterilization. This would make it easy to design a quick little experiment with young fish. One tank without those things & another with, otherwise both the same. Grow the fish & see what happens.

I do not see the need to look straight away to the most complicated improbable explanation for growth inhibition before the obvious probable ones have been eliminated.

Dont mean to offend anyone.
:)

DW

David, Thanks---Jack also said at the ACA in Atlanta, " I never said there was a growth inhibiting hormone, just the possibility of an unknown factor." Joe :-X

[brewmaster15]

Hi Dave,

Hormones are removed by carbon & protein skimmers even in f/w & are easily destroyed by mild UV sterilization. This would make it easy to design a quick little experiment with young fish. One tank without those things & another with, otherwise both the same. Grow the fish & see what happens.
This is not exactly true. Hormones are not easily removed from the water There have been hundreds of studies showing that the simple birth control hormone that people use, easily passes thru waste water treatment plants, and has a very detrimental effect on the sexual development of fish.

http://www.ngo.grida.no/wwfneap/Publication/briefings/Fish.pdf
http://www.northernconcord.org.uk/hormone.htm
http://www.foe.co.uk/pubsinfo/infoteam/pressrel/1999/19990616000107.html
http://news.bbc.co.uk/1/hi/northern_ireland/1897419.stm
http://www.holology.com/hormone.html
http://www.safesoil.com/hormone.htm
http://www.theadvocate.com/stories/090302/new_fish001.shtml
http://www.wsn.org/cwac/healthimpacts.html


This is a very hot area of research ,called Hormone Pollution. it covers hormones being released into the envioronment by humans, as hormones and chemicals that mimic hormones.

Male fish down stream from these waste water treatment plants exhibit partial gender changes, egg/ovary development etc, and growth development changes. Hormones are very persistent.

Whether or not a specific Growth inhibitor exists I don't know. What I do know though is in a tank that is a closed environment, unlike the open waters of the amazon. Biological based chemical, such as the sex hormones that mature fish give off to attract and stimulate a mate have the potential to affect growth, as sex hormones are involved in these very growth mechanisms.

http://www.sparkmd.com/hormones.html
http://www.umds.ac.uk/physiology/banks/sexhorm.html
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Pituitary.html
http://www.theaustralian.news.com.au/common/story_page/0,5744,5539406%255E23329,00.html


IMO, It is likely that a hormone produced by the fish for other evolutionary reasons, can by chance circumstance have an effect on growth, in a closed environment such as a tank.

Also on the notes of Growth hormones. all living things have their growth regulated by hormones.
and though there may not be a specific hormone in fish that evolved as inhibitors, Hormones are often regulated by feedback systems. basically the levels that are present can trigger the expression or suppression of more hormones. Its how an organism regulates its hormone levels. This means that in a tank water situation, any hormones, including Growth hormones could be found at levels that would actually cause a negative feedback loop and act as an inhibitor in the complex system regulating fish growth. Some fish would react differently depending on what their specific stage of development and hormone output is.


Some links on Feedback systems...

http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/basics/control.html
http://www.umanitoba.ca/dnalab/med/pit3.htm
http://www.e-hormone.com/


In general it is avery complex topic, that needs lots more research.
Hth,
al

[wildthing]

If you really want to bring a hormone into this equation I think the concept could be more valid if flipped it on its head.
It could be the absense of a hormome instead of the presence of one.
Instead of an unknown 'hormone' ( GIH) being produced that inhibits growth perhaps the lack of growth is instead attributable to the lack of growth hormone(GH).
GH is known to exist, GIH is not.
Lack of GH could be attributable to several factors .
Genetics...not every baby is a clone, there will always be a range of sizes.
Diet....either insufficient quantity or quality.
Stress....improper tank conditions or bullying could maybe suppress GH production or produce another internal hormone that has that effect.
Discus behaviour shows that size does matter. Fish display & spar constantly to establish pecking order between males & to assess breeding desirability between males & females. Just the presence of a more agressive tankmate or a bigger one could perhaps be intimidating enough to produce runting without the need for GIH. by suppresing theproduction of GH.
Hormnes & Pheromones are proteins...& like many meds & organisms they are 'ripped apart' by UV, it is a question of the correct maximum flow rate, for the experiment I would use all 3 methods combined. Carbon wouldn't be very efficient the pass time would be too long.
just some thoughts

:)

DW

[Steve Rybicki]

DW,

It would seem to me that your explanation of a possible lack of growth hormone, is a more likely reason for small fish not doing well.

[brewmaster15]

DW,
Many breeders on the boards have expressed their opinion that sex hormones are put out in the water by breeding pairs. Many feel that if you want to trigger spawning in one tank, use water from another tank containing a pair that has just spawned.

What are your views on this?
-al

also Dave on a side note, UV alone is not very effective at destroying hormones. If you are to do such an experiment as you outlined you need to look into a special system using titanium oxide as a photocatylist. You can find out more about the system here....

http://news.bbc.co.uk/1/hi/northern_ireland/1897419.stm

[mrespo]

AMEN!

I say let's put this growth hormone thing into perspective. Yes, I believe it is an important factor, but probably an interal one. GH influences development of an individual. I believe that it is far to precious of a commodity to be wasting by releasing it into the water. If anything is released, I would predict that it would be pheromones, or a series thereof.

The genetic part of this equation would be how the individual fish produces GH. This is, how much and at what quantity. It would also involve how well the cells within the fish accept GH and utilize it for growth.

The environmental asspect would involve such ordinary variables such as water quality, food quality, external stressors, and so on. An interaction between the genetics and the environment would produce either mammoth or stunted fish.

The amount each asspect plays varies from individual to individual and situation to situation. That is, you could have the best of environmental conditions, but if GH is produced at low levels, or the cells cannot utilized it correctly, you end up with a stunted fish. This is only moderately true, I believe, in the reverse situation. Your fish could have the very best of genetics, however, if environmental conditions fall to far below optimum, you still end up with a stunted fish. Therefore, both need to be attended to, but it is impossible to say which is more important. I tend to focus heavily on their tank conditions because those are the variables I can control directly and consistantly. While genetics can be manipulated to some degree, they can never be completely controlled (i.e., recessive traits, spontaneous mutations, and the like).

Anyway, that's my opinion.

Thanks for listening.
-Mike

[wildthing]

DW,
Many breeders on the boards have expressed their opinion that sex hormones are put out in the water by breeding pairs. Many feel that if you want to trigger spawning in one tank, use water from another tank containing a pair that has just spawned.

What are your views on this?
-al


I used to think that also, but I have noticed that whether the fish are in the same ( shared) water ( in a central system) or in their own isolated tanks seems to make no difference, now I think that they simply all experience the same 'other' triggers, such as atmospheric pressure changes.
Also, another trigger is a large water change, which would have the effect of diluting any "spawning hormones" & so seems to me to also argue against them.
I think the 'shivering' part of the courtship ritual is important, I think it signals in a broadcast kind of way readiness to spawn, both visually & through the vibrations, to which fish would be extremely sensitive ( through their lateral lines) . The vibrations caused by doing this in the river would cause a much wider ranging signal than hormones & many animals, reptiles & fish are known to use this method of signaling readiness.
:)
DW

Hmmm, Very interesting. Over and over again I read were people add water from pairs that have just spawned to trigger spawning with stubborn pairs (Pheromones). Its never worked for me. :-\ I'm not saying I don't believe it or that hormones are not present in the water. I'm just not so sure what affects they have on other discus. However, I do agreee with David and believe that other factors have more affect on spawning activity. I have pulled numerous pairs often, one right after the other from community tanks and have had discus in adjacent tanks (not on a central) spawn simultaneously.

Pressure Changes, Courtship, Water Changes, Jealousy, Drop in temp... :thumbsup:

Mike

I would have to agree as-well

[April]

well....i have a new pair for 2 weeks....werent doing anything....so i added some water from the breeding pair with fry.....5 gallons two days in a row..and they started shaking right away. today i have eggs.
coincidance? no idea. but i saw a change right away. first day they started shaking . next day started pecking intensely right after. but...could be change in pressure....as today a big rain storm. which also gets them going it seems .

[brewmaster15]

I have to say I have had pretty good luck with it myself.


Maybe the amount of water changed from that breeder tank with the spawners is an important factor. I've generally skipped a water change then taken the water from the tank-- and taken alot of it. Maybe there is a correlation between the amount of hormones in the water and the effect if any that is seen in the fish. If you are doing 30-50% water changes in those tanks... then you are removing that much hormone-if there is any..

The only things I can say for sure is that sex hormones are secreted in all vertebrate urines to some extent, as far as I know there are no exceptions here. The very hormones used in aquaculture spawning aids are derrived from pregnant Horses urine in many cases, or modeled after it.

The other things I can say for sure is there is a wealth of research out there that says that hormones in the water affect fish sexual developement ( see all the links I put up on hormone pollution)

I won't say it works all the time for my pairs, but it has worked often...especially for pairs that have been off the spawn.

I can see the problem though in seeing if it works.. heck the list of spawning triggers is pretty darn long... How do you tell what works and doesn't!? who's got the time to evaluate each methods in an empiracal fashion. I can't even find the time to put out the garbage lately.


-al

[April]

yes...i agree. maybe they were in the mood. but i had been doing 90 percent a day...with colder water and that usually triggers my other pairs. but this one it didnt make them interested at all. when i just removed 5 gallons and added back the 5 gallons twice...bang. maybe they didnt like the big changes.

[Argentum]

Well I just finished reading every single post in this thread!!!
It was very useful and I wanted to revive it to see if anyone has any new insight on the subject.

What I mean if anyone came to a conclusion on what are the GLF (Growth limiting factors) or at least the mechanism which can be used to counter this factor even if it has not been identified.

[kris2341]

here we go again.....

[Rudustin]

here we go again.....No, we are not going there again. The whole thing is bunk!!!! Notice that the posting has been there since yesterday and few if any are going to respond because this has been rolled over by a Mac Truck and it's still road kill!!!

[nc0gnet0]

I would figure it out, but unfortunately my exposure to ILH (intelligence limiting hormone) has severely limited my abilities........

http://www.sherv.net/cm/emoticons/hand-gestures/dont-know-smiley-emoticon.gif

[Argentum]

Guys, I am not here to debate the same old thing, which is the presence of the so called GLH.

What I am interested in is the mechanism that hobbyists and breeders learned to try and optimise the growth of those discus falling behind.

What several people suggested in the thread was segregation by size, what I want to ask is how effective is this and did anyone find more effective methods for achieving the best growth for all discus, given of course that all other variables (nutrition, water changes ... etc) are in good condition

[nc0gnet0]

Lots of clean water and plenty of it is 1st.

Segregation by size can sometimes help, but often some discus are just genetically predispositioned to be larger than others.

If you follow Al's comments in this thread, what he says makes a lot of sense. For a discus to produce such a hormone makes absolutely no evolutionary sense, it would be quickly dissipated and serve no purpose in their natural environment.

As great as jack was, he was a pioneer. That doesn't mean that all the conclusion he came to (and in some cases later changed his mind) were correct.

[Larry Bugg]

Start a different thread that does not mentions GIH. But in actuality your new topic has been beat to death also. Do a search or just read Rick's answer and be done with it.

[Argentum]

Start a different thread that does not mentions GIH. But in actuality your new topic has been beat to death also. Do a search or just read Rick's answer and be done with it.

Not if you have a more systematic approach on that. There are generally accepted common practice, and they are very different from a person to the other.

However they have not been tested in a systematic method, for example lots of clean water, how many is "lots" 50% 100% 200% daily??
stocking density, which is the best? 1 fish per 10 gallon why not 2 or 3 or 1 per 20 ??

I have read several publications addressing theses points why not follow the same methods as hobbyists and get our optimum conditions?
I think combined we can!

[nc0gnet0]

Unless your working with the same batch of fish across all the above conditions, your results are pointless.

[nc0gnet0]

http://forum.simplydiscus.com/forumdisplay.php?40-The-Archives