Debate Topic: I bet a beer that Growth Inhibiting Hormone is a myth...

i concur! 

First,  sorry about beer bet reference moderator. Next time it will be sarsaparilla.

I didnt read your comment as negative and your article refernces were on the money in demonstrating what happens to a fish that is under stress. Hormones like cortisol start flowing which lowers resistance to diseases, other hormones are turned off, which turns you from mister alpha cichlid to I'm gonna hide under the rock cichlid.

As far as what determines who is dominant? My bet (sarsaparilla) is whoever is most aggressive (not size), which could easily be a function of hormones. I have two M. auratus males in the same tank. One is ~30% smaller and he is the most aggressive and dominant  male.  Size only matters when there is tie on attitude.

First lets keep the alcohol references to a minimum as there are kids that view this forum on a regular basis.

Second hormone chemistry is definitely not my area of expertise, but what you are saying makes sense dgreany. It doesn't seem advantageous for a fish to emit a growth inhibitor to control another fish. I have seen stunting of fish by other fish but it is noticeably because of aggression and stress.

Keeper

right, but what causes a fish to be more aggressive than another.... (see above)



dgreany, i was not dissagreeing with u, i couldnt find any study or any solid literature on fish emitting hormones to effect (insert trait here) of another fish.

and im a total smart a**,  but since i couldnt find anyhting on emmiting homornes to another fish i posted with info on hormones in relation to dominance...

cool stuff though, i had never really looked that in depth as to what makes fish tick...

if my cichlids are having a hormone war then may most dominant win

First lets keep the alcohol references to a minimum as there are kids that view this forum on a regular basis.

Second hormone chemistry is definitely not my area of expertise, but what you are saying makes sense dgreany. It doesn't seem advantageous for a fish to emit a growth inhibitor to control another fish. I have seen stunting of fish by other fish but it is noticeably because of aggression and stress.

Keeper

2. What the heck is an evolutionary advantage of a fish spending energy trying to limit the growth of another species in a natural environment?  Before fish lived in tanks, limiting the growth of another species would only be justified (because again see arguement 1, it's likely  expensive) in an environment where a needed resource was direly limited.  Think of the capacity of Tanganika. Is the lake really at a capacity where the fish are resorting to hormonal warfare? And it cant be a new thing we witness in aquariums. Development of endocrine warfare systems takes a few more years than there has been aquariums.

I have not had the pleasure of running into the growth hormone thing you are talking about, however, food for thought for #2 would be that big fish just LOVE to eat little fish.  So expending a little extra energy to keep the food chain nice and fat would definitely be evolutionarily advantageous.  Off to do some research...
Take care,
Mary.

simple:

beer doesn't stunt your growth

now whiskey on the other hand has been known to stunt growth called.....
well, you know ;D

Be happy to buy you a beer, but none of the articles rebut my arguemnt. Your articles demonstrate a hormonal mechanism for fish regulating their own growth, not a tankmates.

And Growth inhibiting chemicals are very well documented in plants (one plant stops another plants growth). But they ae dispersing the chemical into a soil matrix. The dilution factor is nothing compared to a water column.

I'm hoping from your initial comment that the concept of GHI in fish is dead. Is it?

*************DISCLAIMER**************    all the following statements are based on as much effort as a hung over guy can be at 5:30-6:30am on google.   and im just damm thirsty



ok, u read on a forum somewhere yesterday, *sigh*


your answer for ur 1/2/3:  fish are not "hormoning" other fish... but if they could:


read about how increased and decreased "levels" of hormones assign the roles of dominant and sub-dom males.




en.wikipedia.org/wiki/Somatostatin

some background info so everyone knows where im at



www.sciencedirect.com/science?_ob=Articl...e36ae9773747642212c3

read the abstract, this sums it all up nicely, and they tested on Astatotilapia burtoni, if ur lazy, just read the title and the keywords under the abstract.

cichlid.biosci.utexas.edu/Trainor&Hofmann_2006.pdf
full article of above abstract



endo.endojournals.org/cgi/content/abstract/147/11/5119

cant argue with The Endocine Society, sentence 2, not only does it play a role in controlling growth, but it plays into social behavior


aob.oxfordjournals.org/cgi/content/abstract/23/4/612

even strawberries can do it, gosh darn flower ihibiting homone!



now i didnt exactly prove u wrong, but u were asking us to prove to u something that isnt...   so since i had to read that all and spent time finding good information on somatostatin and how if affects the individual fish which in turn is how the fish affects its environment (other fish), which will bring out dominant and subdominant behavior and interactions of fish, and we know that the sub doms live, not neccisarrily as "happy" as they could be but they do, and dominant males thrive;  u owe me a beer:

coors light (draft is preferable)

actually now that i re-read ur title u bet a beer that GIH is a myth... ill take a second beer too:

just make it a car bomb, i'll leave the tip

Hi All;

This

An Introduction;
I've been out of the aquarium main stream (no pun intended) for years, but I'm slowly eaking back in. Willing to bet a beer on anyone who can disprove my rant.

My Diatribe:
In reading a forum somewhere yesterday i came across a  persistant dogma that has chapped my butt from 30 years ago... the thought that a fish can limit another fish's growth through emitting a growth inhibiting hormone (GIH) or Growth Limiting Hormone (GLH). Let me make myself perfectly clear, 'stunting' occurs routinely, but my bet is based on the whether it's caused by hormonal action of a fish on another fish.

Why i think GIH is horsehockey (think BS with a horse);

1. Emission of a hormone into a open waterway is a ridiculously expensive way for a fish to spend energy. The dilution factors of open water would require the GIH to be emitted at a huge cost to te 'emittor'.  Everything a fish does costs the animal energy. They don't waste it.

2. What the heck is an evolutionary advantage of a fish spending energy trying to limit the growth of another species in a natural environment?  Before fish lived in tanks, limiting the growth of another species would only be justified (because again see arguement 1, it's likely  expensive) in an environment where a needed resource was direly limited.  Think of the capacity of Tanganika. Is the lake really at a capacity where the fish are resorting to hormonal warfare? And it cant be a new thing we witness in aquariums. Development of endocrine warfare systems takes a few more years than there has been aquariums.

3. Co-evolution. Even if my question to #2 is wrong, within natural systems, for every fish that trys to limit another fish's growth through GHI, there is an evolutionary process to creates a bypass to the GHI. IN essence a fish wouold be wasting it's time (and energy) trying to limit anothet fish's growth through hormones.

So what causes stunting? My second beer bet goes goes to physiological stress. Fish react, like all vertebrates, to physiological stresses by going through a series of predictable and measurable physilogical changes. In essence, they build up stress hormones (like cortisol) within their systems. These have a range of effects, including stunting.

The goal of these hormones is to protect the fish long term. Most importantly, these stressing agents are synergistic, meaning they add up, one little physiological stress on top of another little physiological stress.  As example, every time a water chemistry factor deviated form the evolutionary 'ideal' that the species evolved, a little stress is accumulated by the fish.  Lighting too harsh or too dark, or now at the correct dark/ight  cycle?, a little more stress is accumulated. Being kept in an artificial environment at artificial population densities (read aquaruim) and being pursued by a predator tank by an artificial predator, more stress is detected.

'Stunted' fish result from one reason. The fish is undergoing physiological stress.  Take big cichlid of your choice and put it alone in 5 gallon aquaruim without water changes and see how big it get. It stunts because of physiological stress factors that accumulate.

And before you write me off as a guy drinking beer and ranting, i guess its only fair to tell you that as a graduate student I measured the synergystic effects of seperate heavy metal toxins on fish, proving (in my mind anyway) they are accumulative. So in essence I'm a guy drinking beer and ranting, with a background... in drinking beer, ranting, and measuring physiological stress in fish.

And another thing. I may be wrong (my wife says it's genetic... to the male sex). Thats why I'm only willing to bet anyone a beer. I would really like to hear of any extremely specific cases of a species that you know of that has the ability to stunt other fishes growth.

God i love this crap.