Are there actual studies for these things???

[discolicious]

The pH debate on another thread has led me to ask some questions I've been thinking about. I respect anecdotal "evidence" and have relied on it heavily, but always prefer actual documenedt studies when available.

I would like to know if any of you are aware of any actual studies having been done with discus on the following. (Most of these questions come from articles I've read on studies with hatchery fish.)

1. Do discus "imprint" on the water conditions they are born in, prefering to maintian those conditions throughout their lives?

2. Any actual adapatability studies to hard water, pH differences, temperature ranges?

3. PARTICULAR INTEREST: Studies concerning the role of the slime coat in discus (other than feeding fry). Studies of other species show that the slime coat plays a role in production of growth inhibiting / stimulating substances (not hormones) that affect fish of the same species in varying ways depending on their developmental phase. Intuition tells me that the prominent slime coat of discus may be the real reason behind the need for frequent water changes with juvies to keep them growing and to avoid stunting. Studies?

4. How do discus recognize the gender of their tank mates? Is it based on behavior, physical markers or possibly even another chemical substance in their slime coat?

5. Are there any long-term detrimental effects from keeping discus at optimal breeding conditions constantly?


If any of you know of actual studies on any of the areas, I'd love to hear about them.

Tom

[Skip]

Whoa! Looks like a phd dissertation to me!

[nc0gnet0]

This is just a guess but such a study, to be conducted properly would require quite a sum of money to do. As a result, your most likely to find only matters of opinions by individual hobbiest and breeders. Our niche market (discus) is too small to justify such a study. That is why you will find most of the studies as they apply to fish farming, and on rare occasion Koi.

[ericatdallas]

There are several studies conducted in Asia for Discus probably due to the low-cost of labor and the high-value of ornamental fish to the local economy. Of course, I haven't looked at it. Probably if you're serious, you should do a thorough literature search. nc0gnet0 is correct, a lot of the research is conducted in relation to farm fish (that bring in much higher stream of revenue or at least, serve the purpose of solving our world food supply problems).

I would start with scholar.google.com, An Aquaculture Journal (http://www.elsevier.com/wps/find/journaldescription.cws_home/503302/description#description), and maybe search a local university for their aquaculture and marine biology text books.

I've been wondering the same thing since I got into Discus... mostly about nutritional needs. Lately, I've also thought about the whole pH, hardness, etc issues. My guess, what's appropriate for Discus is probably a fairly wide range. It also will be dependent on the individual fish. Whether the fish survives, thrives, tolerates, breeds in certain conditions is probably stochastic, with the 90+% probably being in the natural range of the Amazon River.

[Hsunami]

so question just popped into my head reading this post. If slime coat is the one factor that allows the fish to "grow" can't we put like salt to help eat away at the slime coat so theres less of it but enough for the fish to stay health. While still doing large water changes at the end of the day.

[nc0gnet0]

Whether the fish survives, thrives, tolerates, breeds in certain conditions is probably stochastic

How do you define or diferentiate between surviving and thriving? These terms themselves are rather relative. For instance, if you were to compare the survival rate and life expectancy between wilds (in the amazon basin) and domestics, the domestic would win hands down, merely due to lack of predatation.

Rick

[ericatdallas]

3. PARTICULAR INTEREST: Studies concerning the role of the slime coat in discus (other than feeding fry). Studies of other species show that the slime coat plays a role in production of growth inhibiting / stimulating substances (not hormones) that affect fish of the same species in varying ways depending on their developmental phase. Intuition tells me that the prominent slime coat of discus may be the real reason behind the need for frequent water changes with juvies to keep them growing and to avoid stunting. Studies?


Can you cite the studies for the other types of fish?

[ericatdallas]

Here, found something,



Abstract
We conducted a series of experiments to investigate protein content and properties of epidermal mucus from discus fish (Symphysodon spp.), a cichlid species demonstrating parental feeding of larvae with mucus secretion. Observation on the ontogenic development of larval biting behavior showed that feeding rate on parental mucus increased until 15 days of free-swimming period, followed by a decreasing trend, presumably coinciding with the onset of full capacity for exogenous feeding. Analysis of total protein content showed a higher amount in parental mucus (0.73 ± 0.03 mg per ml) as compared to juvenile mucus (0.63 ± 0.01 mg per ml). Electrophoretic pattern also showed similar proteins with differences in levels of expression between parental and juvenile fish mucus. Mass spectrometry analysis revealed the increased expression of a discus type II epidermal keratin in parental mucus. Free amino acid analysis also showed the presence of several essential amino acids such as lysine and phenylalanine in mucus of parental fish.



Kenny Chong, Tham Sock Ying, John Foo, Lam Toong Jin, Alexander Chong, Characterisation of proteins in epidermal mucus of discus fish (Symphysodon spp.) during parental phase, Aquaculture, Volume 249, Issues 1-4, 12 September 2005, Pages 469-476, ISSN 0044-8486, DOI: 10.1016/j.aquaculture.2005.02.045.
(http://www.sciencedirect.com/science/article/B6T4D-4FY3NYT-2/2/8427e31be42fd40fb9e435a4e8560ab3)

I didn't see anything on hormones.

[discolicious]

Eric, I will see if I can locate the article I was reading a while back that referenced the studies that had been done on "slime coat" and growth inhibiting substances. It gave something of a synopsis, and as best I remember it was something to the effect that:

a. It is not a growth inhibiting hormone as many have speculated but exocrine in nature.

b. It is species specific and acts differently at different phases of the fry's development. Initially encouraging growth, but then as the fry reach juvenile stage, it becomes inhibiting. I believe it was speculated that it was probably an evolutionary "tool" for diminishing contenders for breeding rights.

c. In nature, these inhibiting substances are actually weakened and diminished by the dilution of other species' GHS (growth inhibiting substances) in the water. Where only one species is dominant, these substances will have a more noted effect.

That is my "off the cuff" recall of the article, but like I said, I'll look for it this evening.

Tom

[discolicious]

Eric,

This is the article I was reading. He references several studies / writings that I haven't tried to look up yet.

http://wetwebmedia.com/FWSubWebIndex/GrwLmtChems.htm

[Skip]

NERDS!!!!

http://undergradrag.files.wordpress.com/2010/06/nerds1.jpg

[discolicious]

This is just a guess but such a study, to be conducted properly would require quite a sum of money to do. As a result, your most likely to find only matters of opinions by individual hobbiest and breeders. Our niche market (discus) is too small to justify such a study. That is why you will find most of the studies as they apply to fish farming, and on rare occasion Koi.

Yes, you're absolutely right. I had the privilege back in 1993 to work with Auburn University's fisheries department on a project they were doing in partnership with Nicaragua. I was translating their study on how to correctly determine the age of fish (by counting the rings of the otholith (?), a small stone like structure found in the inner ear. It can be split and the rings counted like tree rings, each representing a growing season. Anyway, I was pretty amazed at the amount of grant money involved in the study. I hear the locals eat the discus... think we could pass it off as a potential food source needing in depth study for future hatchery production ?? :)

[discolicious]

NERDS!!!!

http://undergradrag.files.wordpress.com/2010/06/nerds1.jpg

LMAO!!!! I laughed so hard I drooled on my pocket protector!

[Skip]

LMAO!!!! I laughed so hard I drooled on my pocket protector!

http://blogs.villagevoice.com/runninscared/nerds1.jpg

[ericatdallas]

b. It is species specific and acts differently at different phases of the fry's development. Initially encouraging growth, but then as the fry reach juvenile stage, it becomes inhibiting. I believe it was speculated that it was probably an evolutionary "tool" for diminishing contenders for breeding rights.



The only problem I have with that theory is it runs kind of counter to popular evolution theories (I think...). If it's the concentration of hormone (and not specific and targeted chemical attack) that inhibits growth, that implies cooperation. Although over millions of years, it only takes ONE 'cheater' that develops a mechanism to keep growing despite the inhibitor to ruin the system as he/she will continue to breed and pass on that gene. That's why that theory doesn't sit very well with me. What benefit does inhibiting growth pass on to the individual? Cooperation usually only aids evolution when it helps one group out-compete another group (i.e. a predator). Inhibiting your own groups potential seems counter-productive.

I'm not saying it's not possible and the author probably much better educated on the matter than I am and has given it much more thought than I have as well...



NERDS!!!!

Weren't you a science teacher that went back to college for engineering? Isn't that the pot calling the kettle black?

[Skip]

Weren't you a science teacher that went back to college for engineering? Isn't that the pot calling the kettle black?

I do not recall ;)

[ericatdallas]

Here's another one... unfortunately, I don't think I can access it. I can try the library, their computers can access a little more than general university PCs can but maybe you have access to it. Functions for fish mucus. (http://www.springerlink.com/content/r7876w107973hr50/)

Looks like a paper about fish mucus...

[oscarzx]

akiii