Growth hormone?

[RobKenobi]

is it true that adult Discus secrete a growth inhibiting hormone?

This is something I read on another message board

One of my Tanks has 5 Discus in it (a 50 UK Gal) and their sizes are as follows:

1 Blue Turk - 6" to base of tail (grown out mostly on Flake and frozen)
2 Red Turk's - 4 - 5"
2 Blue Diamonds - 3"

The Blue Diamonds were added this last month, and have settled in well. They all get frozen bloodworm twice a day, plus Tetra bits and high quality Flake (flake included twice a week)

Will the growth of the young BD's suffer?

[discuskrib]

can't say i've ever seen any actual studies on this subject so i've just been going along with that proposed theory of hormones in the water. either way, changing the water frequently seems to make the fish happier and keep them healthier.

if anyone has a link to any limnology or other research papers on the subject i wouldn't mind seeing the data for myself.

[brewmaster15]

This ones been batted around awhile....


http://forum.simplydiscus.com//index...;threadid=1295

that'll either help or confuse you more!

-al

[shamsoo]

as per my knowledge every fish baby or adult secrete growth inhibiting matter called phermones, thats why every book and literature says change water on regular basis, so phermones could be diluted and have less effect HTH

[CARY_GLdiscus]

Thats some what true!

But In the discus world IMO females release phermones into the water to attract males when ready to breed.

hth
Cary Gld!

[wildthing]

Oh no...not this again!

IMO there is NO G.I hormone or pheromone.
What evolutionary purpose could it possibly serve & how could it possibly work in the Amazon? What undiscovered organ do they have that produces it?

This thing started when someone misquoted Jack Wattley, who says " factor" but not 'hormone'.
The factors are 'pecking order place', ammonia & nitrates.
change water change water change water.


David

[O]

I agree with David on this! There's absolutely no need for such a hormone in nature. Too much clean water and lots of available food.

O.

[RobKenobi]

first of all, I apologize for opening a can of worms.

I didn't think this statement held much basis in fact. Perhaps a few unsuccessful aquarists needed an excuse as to why their Discus never grew or something.
Anyway, thanks for the link, it made interesting reading. The search feature never turned up anything on this one, but thanks again for your replies guys.

~Rob

[brewmaster15]

hi Rob,
No apology necessary. we all have our opinions on the subject.

In my mind there is no doubt that fish put hormones into the water. All vertebrates, and many other living creatures do this. Sex hormones , sex attractants , etc. a Sex hormone causes physiological changes in a an organism. Though there may not be a specific "growth Inhibiting hormone" others hormones can indirectly affect the biological process, and impact growth.

Think about this...
1. There are volumes of scientific studies and data that show that fish, when exposed to sex hormones from Human birth control pills, and chemicals that mimic them , change sex, or exhibit sex characteristic changes. This has been studied extensively in the water down stream of our sewage treatment plants, and in the Great Lakes of the USA, as well as in many european countries. Hormone pollution has become a major concern. Why is this possible? Because the genes for hormones are conserved across species...meaning they are very similar in all vertebrates. The fact that fish respond to hormones in the water indicates to me that they can detect them, and the only reason they would have evolved to be able detect them is because they use them.

2. Sex hormones effect on growth. If you add testosterone based hormones to the water... what happens? The fish respond by physiologically changing... the brighten up, reds become distinct... The become sexually mature even at 2-3 inches. They may even spawn. what is a concern commonly shared by everyone as to the side effect of this "hormone treating"... The Hormoned fish is often runted. There is a clear cut example of a Hormone treated fish... being runted... or having its growth inhibited, in this case by the indirect effect of a sex hormone. again... this shows that discus have the ability to respond to hormones, and most likely secret them.

3. some food for thought on the usefulness of hormones in the rivers of the Amazon. One might think that in a river it would serve no purpose... as any hormones would be washed away. I spent a few years working for the state of connecticut at an experimentation station. while there I was involved in a forest health project where we were interested in a certain caterpillar species...called the hemlock looper. To make the story short.. we tested a pheremone that was suspended in the trees. Even on a windy day the pheremone attracted male moths to the trap from incredible distances... miles most likely. By my thinking there is not much of a difference between wind as medium and water.

These are all extreme examples.. but often times when a researcher is looking for mechanisms, you start with these exaggerated experiments and then tailor them to a more relevent model.

My conclusions here.. Though I do not believe that there is any evidence that a hormone evolved to inhibit other fishes growth. I believe there is more than sufficient evidence to show that fish can have their growth inhibited by homones... particularly sex related ones.

How I see it working in a tank of fry... scenario 1. The fastest growing ones, will have higher amounts of sex hormones being produced (this is true of all vertebrates), some of which will be put out in the water in their waste. (pregnant mares Urine is a source of hormones used in experiments and fish breeding). These hormones will have an effect on the other fry. The slowest growers will show the biggest effect..

scenario 2.... The excreted Hormones accelerate some physiological processes in all the fry, but the smaller/slower growers are not developed enough to fully use respond and so they fall behind in growth.

scenario 3... Clueless on how it works but pretty sure some kind hormones are excreted into the water in the fish waste... This has the potential under an unknown set of conditions to have an affect on the growth of fish.

-al

[RobKenobi]

What a great post, thank you
The knowledge on this board is astounding to say the least.

I knew that the growth of smaller fish would be affected by larger fish kept in the same tank, but I didn't consider the extent (big or small) or the complexities of such effects.

When all is said and done, water changes seem to be the answer to (or play the main part in dealing with) all problems that may occur with our fish. Now I understand why allot of keepers place so much emphasis on such a simple thing as water changes.
Of course how much and how often is down to personal preference, but the general consensus seems to be the more the better

This is the best hobby and the best message board. Hopefully one day I can contibute more than just questions.

Take care all

~Rob

[CARY_GLdiscus]

Nice write up Brew,

That I'll end Wth a link! Now its not a discus link! But about Fish + pheromone. Now I know if It could happen in the greatlakes then Why not in the amazon? I Believe the SLOW running water during SPAWNING season would Would be Ideal! since over half of the worlds Tropical fish come from there. anyways have a look! hee.hee.hee...


http://www.seagrant.umn.edu/seiche/jan.01/art03.html


http://www.fw.umn.edu/mnafs/abstracts/1998abstracts.pdf



Peter W. Sorensen - ... with the actions of hormones and endocrine disrupters (EDCs) on fish behavior; this interest is derived from my discovery that many fish pheromones are hormone ...
http://www.fw.umn.edu/Personnel/Faculty/Sorensen.html
Alarm Pheromones in Fish - Alarm Pheromones in Fish: Functional and Evolutionary Aspects. Christopher ... This seems to be the case in fish alarm pheromones. The ...
http://www.colostate.edu/Depts/Entom...994/bosio.html
Minnesota Impacts - Fish: Control via Pheromones - ... Using the goldfish as a model, we have discovered that fish pheromones (the term given to chemical signals between the same species) are derived from hormonal ...
http://www.extension.umn.edu/mnimpac...projectID=2806
Sea Grant Seiche--the smell of fear - ... Pheromones are already common for controlling insects. Generally, insect pheromones are species-specific and the same seems true of fish pheromones. ...
http://www.seagrant.umn.edu/seiche/jan.01/art03.html
News - ... We’ve been finding over the last two years that there are specific pheromones that do encourage fish to feed.” Dr Andy Moore. ...
http://www.cefas.co.uk/news/news041102.htm
About Infiltration - Pheromones and Fish. ... The studies suggest that fish can release immune suppressing pheromones (hormones) in overcrowded conditions. ...
http://www.koikichi.com/about/articles/pheromones.html
Peter W. Sorensen - ... Stacey, NE and PW Sorensen. 2001. Fish hormonal pheromones. In: Hormones, Brain, and Behavior. (eds. D. Pfaff, D. Arnold, A. Etgen, S. Fahrbach, and R. Rubin). ...
http://nash.cbs.umn.edu/BBBG/directory/sorenson.html
Putting the Passion into Fish Farming - Sex on the Farm #25 - ... In solitary species, the female fish will release pheromones to indicate to prospective males that she is ready to mate. ... Hormones as sex pheromones in fish. ...
http://www.syndel.com/spawning/sex_on_the_farm_25.html
Fish talk - ... How do fish communicate using pheromones? ... Social pheromones exist as well, cueing fish in on whether or not they are too crowded together or lonely etc. ...
http://allsands.com/Science/Animals/...ati_sey_gn.htm
Pheromones: Resources on Net - ... Sorensen is a specialist in physiology and behavior of fish, olfaction, fish reproductive biology, pheromones, control of exotic species of fish. ...
http://waru.life.nthu.edu.tw/~frankc...omone/res.html

[aqua]

Couple months ago, I put a 2in Marboro into 100gal tank along with 12 other young adults (4-6in). He never got pick on and always got full belly of food at feeding time. This fish is about 5in now. Very round and aggressive eater. Well, all other fish in the tank are blue. So, I guess he get the special treat.