Fish growth hormones

[limnologist]

Ok, Ive been studying aquariums and fish for the past 11 years hoping to be a limnologist and Ive come to a problem that stumps me. I cant seem to find much info on fish growth hormones, namely, in relation to their habitat. For example:
When a fish (lets say a bullhead catfish) lives in a very immensely large body of water (a very large lake) it usually gets a couple feet long, but the same species, with the same food and weather pattern in a smaller body of water grows to only half this size. Now, lets take a bullhead and put him in a 100 gallon tank, everythings fine and he gets about a foot long. but, put one in a 40 gallon tank and people start calling it abuse. At first thats perfectly understandable, but then, somebody said that no matter how small the outside of the fish's body is, its organs will continuosly grow. why does that sound wrong to me? I find it plausible to say that a fishes growth hormones can and will react to its habitat size, temp, lighting, and food availability (the fact that they react based on their surroundings helps with this belief), thus, a smaller habitat will make a smaller fish (already demonstrated in the lake to pond ratio).

surely there is an expert who can help me understand?

 

[treemanone2003]

It's always been one of the hottest discussions in the hobby. I'm no scientist but it would be my opinion and experience that a stunted fishes organs will continue to grow. Although I've never dissected one after death, nor did I ever think to, I can't confirm anything about internal organs as I simply based it off of the eyes. I had the displeasure of learning the hard (and costly) way about Discus until I did more and more research and finally got the grasp on them. My methods now are a direct result of doing things the wrong way and learning from my mistakes. I can't stress enough to anybody (even if I'm talking to myself) willing to listen how important some factors, IMO play in a fishes life.


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[Delapool]

Ok, Ive been studying aquariums and fish for the past 11 years hoping to be a limnologist and Ive come to a problem that stumps me. I cant seem to find much info on fish growth hormones, namely, in relation to their habitat. For example:

When a fish (lets say a bullhead catfish) lives in a very immensely large body of water (a very large lake) it usually gets a couple feet long, but the same species, with the same food and weather pattern in a smaller body of water grows to only half this size. Now, lets take a bullhead and put him in a 100 gallon tank, everythings fine and he gets about a foot long. but, put one in a 40 gallon tank and people start calling it abuse. At first thats perfectly understandable, but then, somebody said that no matter how small the outside of the fish's body is, its organs will continuosly grow. why does that sound wrong to me? I find it plausible to say that a fishes growth hormones can and will react to its habitat size, temp, lighting, and food availability (the fact that they react based on their surroundings helps with this belief), thus, a smaller habitat will make a smaller fish (already demonstrated in the lake to pond ratio).



surely there is an expert who can help me understand?

Following.

The pictures I have seen of stunted growth (assuming the website is not making things up), the fish didn't have a nice streamlined shape to it and just looked off (can't explain it any better). I've also wondered on this. The hormones make sense, perhaps it is not that the organs will explode but the hormones would have to act equally on all growing organs? So idk maybe the kidneys grow a bit bigger than they should to fit the smaller fish or something so it's shape becomes wrong. I'd imagine that would reduce life span as well. Thoughts?

 

[jlk]

Ok, Ive been studying aquariums and fish for the past 11 years hoping to be a limnologist and Ive come to a problem that stumps me. I cant seem to find much info on fish growth hormones, namely, in relation to their habitat. For example:
When a fish (lets say a bullhead catfish) lives in a very immensely large body of water (a very large lake) it usually gets a couple feet long, but the same species, with the same food and weather pattern in a smaller body of water grows to only half this size. Now, lets take a bullhead and put him in a 100 gallon tank, everythings fine and he gets about a foot long. but, put one in a 40 gallon tank and people start calling it abuse. At first thats perfectly understandable, but then, somebody said that no matter how small the outside of the fish's body is, its organs will continuosly grow. why does that sound wrong to me? I find it plausible to say that a fishes growth hormones can and will react to its habitat size, temp, lighting, and food availability (the fact that they react based on their surroundings helps with this belief), thus, a smaller habitat will make a smaller fish (already demonstrated in the lake to pond ratio).

surely there is an expert who can help me understand?

I am not sure if I understand exactly what it is you are asking. Are you asking if fish hormones have an effect upon fish (ie, small environment equates to a small fish) or are you inquiring as if its possible for a fish to decease living as the result of organ expansion (or something to this affect)?

This is a multi-tiered inquiry as numerous factors come into play beyond just simply an inadequate environment. In nature, an inadequate environment results in poor water quality, excessive stocking, insufficient food supply, reduced oxygen levels, easy predator access and an excess of hormones that affect growth and reproduction (which relates directly back to poor water quality) among other issues. Its been scientifically documented that fish in natural environments under these conditions are exponentially more likely to suffer from a myriad of diseases, to grow improperly (do not reach genetic potentials and/or are deformed in some capacity), fail to reproduce and have diminished lifespans. Most people refer to this phenomenon as stunting.

While organ explosion as the result stunting is more myth than reality, excessive growth of the bony structures such as the spine or rib cage (in comparison to body size and structure) has been documented as has differentiation in organ structure. A stunted fish in natural environment will be shorter in stature but will have a much deeper breadth/larger head and possibly a more curved appearance to accommodate organs and spinal growth. Health issues follow suit and this is probably the most commonly seen in the goldfish arena (fish that develop a curved or 's' spine and deep body as they age within restricted conditions). Health issues also arise from the afore mentioned concerns (water quality, lack of nutrition, excess hormones, reduced immunity, overstocking, disease, etc).

Once again referring back to goldfish, it is well accepted within the goldfish community that water and hormones play a crucial factor in health and growth. Growth inhibiting hormones as well as toxins (and to a lesser degree, disease) within the water are reduced by frequent, big water changes. This has been widely accepted for well over a millennia in the goldfish community as the result of experience prior to any 'scientific' knowledge to justify doing large, frequent wcs. Water quality and hormone levels are key factors for growth as is nutrition. These factors are crucial to any fish's health, well being, growth and reproductive capabilities. Limiting water quality and nutrition has detrimental affects upon a fish across the board.

Not sure if I exactly answered your query, but, yes, hormones and toxin levels are a factor in fish growth and health. They directly interplay with each other but, no, fish are not known to explode as they will suffer an untimely demise from numerous other factors long before this could ever potentially, possibly happen. Under inadequate, unhealthy conditions, stunting is an inevitable consequence and there are a plethora of negative issues that accompany it. Hope this helps a bit! Feel free to ask questions!

 

[limnologist]

what im trying to get at is if it's possible for a fish to live in a very small enviroment (small tank), grow to half its eventual size, and still be perfectly healthy and have a full life span. I was attacked by many different "aquarium Experts" on frogforum because I had said that I kept a bristlenose pleco in 10 gallon aquarium and its been 6 years now and its only a few inches long. Ive seen no adverse effects on its health as of yet and has even bred once (with succesful outcome).
5 years ago, when I noticed the pleco was healthy but not growing, I got really interested in dwarfing and stunting. I did a lot of research and everything I read eventually went along the lines of "you should always spend a ton of money on tanks because you cant keep fish in tanks that are too small or else they will get sick and die from stunting". Now, since then, Ive kept 3 common plecos, 2 bristlenose plecos, 3 bullhead cats, many large cichlids (including the illustrious Jaguar cichlid), plenty of gouramis, all native sunfish and bluegills, large and small mouth bass, knife fish, pictus cats, and koi in ten gallons and 20 gallon tanks. never once did i ever see any detrimental effect to their health and (as far as I know) they are all still alive (I sold most of them to friends). I still own a male and female bristlenose, 2 bluegill, and 3 bullhead cats. I think adaptability is the main player in this matter, I also think thats why various fish react differently to decreased habitat size (the discus is an example).
Im going to be very disappointed if anyone pulls the "animal abuse" card right now because I put my life and my very essence into the well being of my pets.

 

[JRT83]

My 125g tank is home to my 10" male jaguar cichlid and thats it... Why would you even consider housing a fish that can reach 18+" in a tank thats less than 3 ft long and a foot wide? For research purposes? Water conditions deteriorate rapidly in small tanks like that and large cichlids like that will have no room to swim... May not be animal abuse but you're definitely not giving your fish a good home.

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[BillD]

I saw a picture many years ago of trout grown in a jar, until they could no longer move. I have been unable to find this photo but I did see further info on it. Apparently the water in the container was changed 120 times an hour, so waste and such had no effect on the growth rate. It would seem neither did the size of the container. So, if in fact there is a hormone exuded by fish that reduces growth in crowded conditions, it certainly wasn't present in this particular case. It would seem that the size of the container is a less an issue than the water quality. I have always believed this and my limited experience breeding angels confirmed it.

 

[limnologist]

My 125g tank is home to my 10" male jaguar cichlid and thats it... Why would you even consider housing a fish that can reach 18+" in a tank thats less than 3 ft long and a foot wide? For research purposes? Water conditions deteriorate rapidly in small tanks like that and large cichlids like that will have no room to swim... May not be animal abuse but you're definitely not giving your fish a good home.

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he was an inch long baby and had all the room he wanted to swim. I paid immense amounts of attention to the water to keep it perfect and he only grew to 3 inches long. he's still alive (though he is in a much larger tank now) but the three years I had him, he grew onlt two inches and was perfectly healthy the entire time (he was very smart as well). I guess, at this point, Im doing it for research.

 

[JRT83]

he was an inch long baby and had all the room he wanted to swim. I paid immense amounts of attention to the water to keep it perfect and he only grew to 3 inches long. he's still alive (though he is in a much larger tank now) but the three years I had him, he grew onlt two inches and was perfectly healthy the entire time (he was very smart as well). I guess, at this point, Im doing it for research.

My jag is 2 years old and 10"... A stunted fish is not a healthy fish no matter how you look at it, neither is a 3 year old Jag that's only 3"-4" long. It's somewhat laughable that you'd call that "perfectly healthy." Just because we CAN keep certain fish in any size tank we want, doesn't mean we SHOULD. Saying it's strictly for research is fine, but please don't go recommending this way of fish keeping to other hobbyists who may not know better.

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[limnologist]

I saw a picture many years ago of trout grown in a jar, until they could no longer move. I have been unable to find this photo but I did see further info on it. Apparently the water in the container was changed 120 times an hour, so waste and such had no effect on the growth rate. It would seem neither did the size of the container. So, if in fact there is a hormone exuded by fish that reduces growth in crowded conditions, it certainly wasn't present in this particular case. It would seem that the size of the container is a less an issue than the water quality. I have always believed this and my limited experience breeding angels confirmed it.

Has anyone ever heard of the famous "Korad Z. Lorenz"? he wrote a book called "Solomons Ring" and in it, he recalled a jewelry store he lived close to that had a regular sized goldfish bowl with a bass inside it. the keeper of the store built his own filtration system that constantly cleaned and changed the water. he said the fish lived for over 20 years. (though, I may be thinking of the wrong book. he wrote a few books).

 

[limnologist]

My jag is 2 years old and 10"... A stunted fish is not a healthy fish no matter how you look at it, neither is a 3 year old Jag that's only 3"-4" long. It's somewhat laughable that you'd call that "perfectly healthy." Just because we CAN keep certain fish in any size tank we want, doesn't mean we SHOULD. Saying it's strictly for research is fine, but please don't go recommending this way of fish keeping to other hobbyists who may not know better.

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Calm down, Im sensing a bit of hostility here haha.
Define for me first, what exactly do you say is "stunting"?
I would call stunting, permanently damaging the animal in question and shortening its life span and body size. I am stating that the fish I had for the time would not grow. Im also stating that it should no signs of being unhealthy. and also, when I sold him off to a friend and that friend (a six year hobbyist) put him in a 100 gal tank, the fish grew to about 11 inches long and is a perfectly healthy male with no defects.

 

[jlk]

what im trying to get at is if it's possible for a fish to live in a very small enviroment (small tank), grow to half its eventual size, and still be perfectly healthy and have a full life span. I was attacked by many different "aquarium Experts" on frogforum because I had said that I kept a bristlenose pleco in 10 gallon aquarium and its been 6 years now and its only a few inches long.

Will a severely stunted fish be perfectly healthy and fulfill its expected life expectancy? The answer is no. Neither will any other animal (including a human).

As our forum as well many other aquatic forums adhere to the standards of ethical fishkeeping, your personal decisions in respect to the care of the creatures that you may keep are your own, however, your standards can not be condoned or encouraged in any manner. It would be worthwhile to spend some more time researching the short and long term implications of stunting and stress on the morphology aquatic animals. There is quite a plethora of information available.

 

[absolutangel04]

Are you in college? I only ask because you said you wanted to be a limnologist and are studying. Well, many good valid points of study will come form peer reviewed journals. The downside is that most good peer reviewed science journals are not that easily accessible to the public. However, any half decent university will have all sorts of access to further your studies.

Another reminder is that people have their own feelings on ethical fish keeping, and you can't just expect that nobody will call foul when they see a person treating an animal in a way they feel is unethical. While we strictly forbid personal attacks and rudeness, people are quite able to question your practices in a polite way. It is a logical fallacy to assume that because you care that you are doing the right thing. That said, I am not criticizing you. I personally do not believe bnp belong in a 10g tank, but I know other people who also have them in one and even use them as breeding tanks.
Things like this are indeed multifaceted as there are multiple growth contributors like jlk said. Another thing to keep in mind is that many fish in the aquarium industry have been bred for many generations to deal with poor situations. Bettas, goldfish, and plecos are a few that come to mind where individuals suffer terrible situations all the time but are part of the aquarium industry because they don't die instantaneously in less than ideal conditions.
There is also part of this debate that is in morphology (what is actually happening to the fish) and part rooted in ethics (what sort of situation do you think it is acceptable to put an animal in who is under your care). What can you do versus what should you do.
In my experience, I have seen a lot of fish put into tanks too small and virtually none of them ever lived out their full life span. Though, that is a tough one to judge when you are dealing with organisms that live for many years. I know multiple plecos over 20 years old. Plecos can be especially tough. Sometimes that is when the can versus should debate takes over. Also, there is much disagreement about what quality of life a fish can enjoy, and how much they deserve ect.
Apologies for the long winded response, but the question is broad. Are you mostly interested in the science aspect of it?

 

[Delapool]

Didn't someone do a kind of study on this in collage where they had two tanks of fry set up? One tank got more regular water changes and the fry grew bigger from memory? I think it was him and a room-mate had a tank each.

Tank wise I think it is a bit like the zoo. In the old days animals had small pens and nowadays have larger holdings designed for them. Still not the same but more natural imo.

But then what about fish farms?? I've seen pretty huge stocking rates there. Are we kidding ourselves a bit or just pragmatic?

 

[Masha]

Fish farms might be different though . Those fish are grown super quick and then killed for their meat. They don't live that long. I saw a fantastic presentation about fish farming it's pretty amazing how they do things. Apparently some fish farming techniques are dodgy, but not all fish farms are the same.

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[limnologist]

I think it would be something good to look into. Even the added facts that fish never stop growing and also that they vary in size in accordance to their habitats in the wild help with the idea that they grow according to the habitat conditions. Fish are very adaptive.

 

[limnologist]

Are you in college? I only ask because you said you wanted to be a limnologist and are studying. Well, many good valid points of study will come form peer reviewed journals. The downside is that most good peer reviewed science journals are not that easily accessible to the public. However, any half decent university will have all sorts of access to further your studies.

Another reminder is that people have their own feelings on ethical fish keeping, and you can't just expect that nobody will call foul when they see a person treating an animal in a way they feel is unethical. While we strictly forbid personal attacks and rudeness, people are quite able to question your practices in a polite way. It is a logical fallacy to assume that because you care that you are doing the right thing. That said, I am not criticizing you. I personally do not believe bnp belong in a 10g tank, but I know other people who also have them in one and even use them as breeding tanks.
Things like this are indeed multifaceted as there are multiple growth contributors like jlk said. Another thing to keep in mind is that many fish in the aquarium industry have been bred for many generations to deal with poor situations. Bettas, goldfish, and plecos are a few that come to mind where individuals suffer terrible situations all the time but are part of the aquarium industry because they don't die instantaneously in less than ideal conditions.
There is also part of this debate that is in morphology (what is actually happening to the fish) and part rooted in ethics (what sort of situation do you think it is acceptable to put an animal in who is under your care). What can you do versus what should you do.
In my experience, I have seen a lot of fish put into tanks too small and virtually none of them ever lived out their full life span. Though, that is a tough one to judge when you are dealing with organisms that live for many years. I know multiple plecos over 20 years old. Plecos can be especially tough. Sometimes that is when the can versus should debate takes over. Also, there is much disagreement about what quality of life a fish can enjoy, and how much they deserve ect.
Apologies for the long winded response, but the question is broad. Are you mostly interested in the science aspect of it?

I am in college, and I'm mostly interested in the science aspect of the idea. Also, I certainly enjoy long, well thought replies or explanations haha.

 

[absolutangel04]

Ok. I definitely suggest looking into the library database for peer reviewed journals about the topic if you can. There will be somewhat different results since most experiments published like that will be about salmonids and such.
Such studies will of course not really get into the ethics of the debate though, which are a factor for most fish keepers.


There are a lot f types of fish farms. They still have fish, so while the situation is different, there is not reason to disregard it entirely, just take it in context. Also, not all fish farms raise and kill fish. There are also many hatcheries that raise and release fish into the wild. Certainly home aquaria is a different beast than a large scale fish farm, but it is just common sense that not everything can be laterally shifted. I learned a ton about fish when I was in college getting a degree and working for USFWS even though that was dealing with wild populations.

Back to the original point, sometimes it seems to happen that you will find a "dwarfed" fish that was raised in a tank that was too small for it. As has been said, clean water is a huge part of growth in home aquaria. Though, it is highly arguable that such fish are actually living out their full life spans to the proper extent. Also, for every miniature you see, you will also see dozens of dead fish, and deformed fish who have a hard time swimming and eating. It is one of these things that you need to look into what can happen rather than use a single instance of as evidence. Personally, I have seen a lot of fish kept in too small tanks, and none really lived out its lifespan like if the owner had just upgraded. 10g tanks are very common starter tanks in the hobby, and many new people who get them have no clue how to stock them. Lots of fish die this way. Now, plecos and goldies have this crazy ability to live through many ridiculous situations, and it is part of why they are sold so much. My cousin kept goldfish in a bowl when we were kids, and she had a pair that were very long lived. One died in 7 years, the other after 13 years. The whole time, they lived in the bowl. Now, that may seem like a good enough deal, until you consider that many goldies kept in proper situations live into their 20s. Also, I would not use this one time as an example to say that stunting does no harm since thousands of other goldies die in bowls every year, even when the water is kept clean. There is a difference the effects overall, and the fish that overcome odds. I personally have never red any any data that actually concludes that stunting fish is a good thing in any situation. You want a smaller fish? Then get a smaller fish. I see no reason to cram fish into tanks too small for them to reach full adult size when you can just get a smaller fish...

Of course, when dealing with aquaria, you will eventually end up at the point of "to each their own."

 

[Mebbid]

Didn't someone do a kind of study on this in collage where they had two tanks of fry set up? One tank got more regular water changes and the fry grew bigger from memory? I think it was him and a room-mate had a tank each.

Tank wise I think it is a bit like the zoo. In the old days animals had small pens and nowadays have larger holdings designed for them. Still not the same but more natural imo.

But then what about fish farms?? I've seen pretty huge stocking rates there. Are we kidding ourselves a bit or just pragmatic?

I have a great example of this with a good friend of mine. She had a large batch of guppy fry (around 50) that was kept in a 10g tank. She changed out the water as needed to maintain a relatively acceptable concentration of nitrate in the tank. However, these fish never really grew to full size. It was at that point I suggested that she put some into a 2 quart HOB breeding box for a while and see how things change. The 10 that she put in the HOB breeding box grew a lot larger than the ones that were in the 10g in a short amount of time. I'm sad that I didn't take pictures at the time for just this reason. Arguments can be made that it's not a scientific example and to that I agree, but there is absolutely no denying that there was something about the over pack 10g tank that slowed the growth of guppies down. Especially, since the size of the container they were moved to was miniature in comparison. With water changes being done and nitrate controlled, I can only theorize that it was hormones in the water being produced by too many fish.

I think it would be something good to look into. Even the added facts that fish never stop growing and also that they vary in size in accordance to their habitats in the wild help with the idea that they grow according to the habitat conditions. Fish are very adaptive.

Whenever I see a discussion such as this pop up I like to refer people to an article I found at one point.

Stunted growth means stunted lives — Seriously Fish

 

[Mebbid]

"you should always spend a ton of money on tanks because you cant keep fish in tanks that are too small or else they will get sick and die from stunting".

I don't know about you, but I find that it's entirely affordable to buy a larger tank to fit most species of fish in nowadays aquaria.

Im going to be very disappointed if anyone pulls the "animal abuse" card right now because I put my life and my very essence into the well being of my pets.

You may be disappointed, but that is exactly the heart of the issue in these discussions. Is it "ethical" to put a fish in a tank that is too small for them. It's VERY common to see the actions of tank size and stress on many different fish. This is ESPECIALLY true in salt water. Discus and Rainbows are the two most notable examples of this for fresh water that I can think of off the top of my head. You can see a difference in how they act when they are in too small of a tank. This is something I've seen for myself. Even in bettas, they act 100% different between being in a small vase and a 10g or larger tank. They suddenly become more active, more interactive, and appear to be generally happier than the sulking they do in a tiny vase.

On the other side of the spectrum it's much much easier to see in salt water fish. Especially since in these tank water quality is almost never an issue. Tangs are by far the largest example of this in which a tang that is in too small of a tank will stress out and die 99 times out of 100. I have personally never seen an example of long term success in keeping sensitive fish in too small of a tank on the salt water side of things and these tanks tend to hang around a lot longer than fresh water does.

Improper tank sizes create stress on the fish and I would personally be amazed if you could find any contradicting information on that.