Fish size

The reason I am bringing this up is that I have seen several species of fish that will not out grow their aquarium. the last one I experimented with wasn't a native fish but was a irredecsent shark. It was housed at first in a 15 gallon tank but I quickly put it in a 125 after buying it from the local fish store. it lived several years and never exceded about 10" even though it spent the summer in a large yard pond. I fed it lots of live food like daphnia, black worms and plants. It lived in a tank with two dozen inland silversides, a mormyrids, blue spotted sunfish (which spawned several times) glass catfish and cardinal tetras. the fish was eventually eaten while in it's summer pond home by an egret. Is it too much to say that a fish that in nature attains a certain size should do so in an aquarium? I have read that in some lakes the fish stay small due to environmental factors. Has anyone else seen this? Is the old rule of thumb that a large fish will out grow it's environment not true? I once kept a gold fish in a small bowl for several years and it never got big but goldfish in a pond can weigh several pounds. have we been promoting a truism that isn't necessarily true?

Fish growth is very conditional on multiple factors both in the wild and in captivity. (We all know this..Don't we?)
I do believe it is mostly an ethical issue as far as hobby preaching is concerned.

Fish cannot outgrow aquariums and feet cannot outgrow shoes.

THAT IS JUST DOWN-RIGHT F#&*$*$D up!!!!

wow

fish can get too big for an aquarium, but like Todd said, its more of an ethical/moral issue...the fish won't break the glass but htat doesn't mean the tank is big enough....

What about the claim that fish produce growth inhibiting hormones in crowded conditons and frequent water changes and GAC help dilute those hormones and promote growth?
Not sure if I believe it myself, wondering about other opinions.
It seems obvious that SOME factors cause fish in certain situations to mature at smaller than normal size and never realize full growth potential.
There's a tiny fire pond near my Dad's place that has stunted pumpkinseeds. They seem to top out at ~ 4-5 inches max. The over abundant golden shiners seem to top out at 3-4 inches. Both seem to be less than half their potential size. [interestingly, eels that enter as elvers from the near by ocean seem to have no trouble growing to ~ 2 feet and fat!]
I'm tempted to take a few of the pumpkinseeds and try and breed 'em. Wonder what size I could get in my tank?

Fish growth is very conditional on multiple factors both in the wild and in captivity. (We all know this..Don't we?)
I do believe it is mostly an ethical issue as far as hobby preaching is concerned.

I'm not sure what you mean by an ethical issue, I didn't exactly shoe horn the 10" fish into the 125 gqallon aquarium or the large yard pond. I am questioning the old wives tales that a fish will out grow it's tank, I've kept goldfish when I was young in small bowls and they stayed small but gold fish raised in a pond grew huge by comparison.

What about the claim that fish produce growth inhibiting hormones in crowded conditons and frequent water changes and GAC help dilute those hormones and promote growth?
Not sure if I believe it myself, wondering about other opinions.
It seems obvious that SOME factors cause fish in certain situations to mature at smaller than normal size and never realize full growth potential.
There's a tiny fire pond near my Dad's place that has stunted pumpkinseeds. They seem to top out at ~ 4-5 inches max. The over abundant golden shiners seem to top out at 3-4 inches. Both seem to be less than half their potential size. [interestingly, eels that enter as elvers from the near by ocean seem to have no trouble growing to ~ 2 feet and fat!]
I'm tempted to take a few of the pumpkinseeds and try and breed 'em. Wonder what size I could get in my tank?

I thought of the growth hormone thing but I did partial water changes on a regular basis and the yard pond helpd at least 2000 gallions and was set up so rain would run out on the ground instead of running it over. We usually get a lot of rain here in the summer, hurricanes seem to deliver plenty of rain. I've read a couple of papers on the fish stunting in ponds due to various environmental factors. could we be accedentally reproducing these factors in aquariums?

THAT IS JUST DOWN-RIGHT F#&*$*$D up!!!!

wow

fish can get too big for an aquarium, but like Todd said, its more of an ethical/moral issue...the fish won't break the glass but htat doesn't mean the tank is big enough....

Again i say I didn't exactly have to shoe horn a 10" fish into a 125 aquarium.

Fish growth is very conditional on multiple factors both in the wild and in captivity. (We all know this..Don't we?)
I do believe it is mostly an ethical issue as far as hobby preaching is concerned.

ethical issue? Yes if it is keeping a six foot fish in a five foot aquarium but how could this relate to keeping a 10" fish with the potintial to grow to one meter in a six foot aquarium but the fish never grows larger than 10"

Edited by teleost, 08 March 2008 - 02:53 PM.

ethical issue? Yes if it is keeping a six foot fish in a five foot aquarium but how could this relate to keeping a 10" fish with the potintial to grow to one meter in a six foot aquarium but the fish never grows larger than 10"

It does not and that was not my point...
The common usage of this "old wives tale" is one of ethics and animal welfare, that is do not put big fish in small tanks. In my opinion I'm with you on this it is a played out and rather false ideology to say a potential large fish will always out grow their tank. This is not true... I keep Gars, I'm very aware of just how false it is to assume Wild max size can be achieved in captivity. I have had one Longnosed gar in a 240 gallon tank for over 9 years and it is just a little over 16 inches. It just grew that way and has never really got much larger. It has the space to grow out but it has not. In the same tank I had another longnosed reach over 2 foot and it had to be moved.

As said before Fish and the growth of fish is multifaceted and can vary heavily depending on multiple factors not just one.
So to answer your question:

have we been promoting a truism that isn't necessarily true?

The answer is yes....

It does not and that was not my point...
The common usage of this "old wives tale" is one of ethics and animal welfare, that is do not put big fish in small tanks. In my opinion I'm with you on this it is a played out and rather false ideology to say a potential large fish will always out grow their tank. This is not true... I keep Gars, I'm very aware of just how false it is to assume Wild max size can be achieved in captivity. I have had one Longnosed gar in a 240 gallon tank for over 9 years and it is just a little over 16 inches. It just grew that way and has never really got much larger. It has the space to grow out but it has not. In the same tank I had another longnosed reach over 2 foot and it had to be moved.

As said before Fish and the growth of fish is multifaceted and can vary heavily depending on multiple factors not just one.
So to answer your question:
The answer is yes....

I guess my nexg question is why has this be promoted by so many people? Of course there is the other side of the coin, there are fish thaqt will grow to way too large for anything like a reasonable home aquarium no matter what. I saw a pacu that had to weigh 40 or 50 pounds in an aquarium it could hardly turn around in. It would appear to be a complex question and answer. I know i was told it was impossible to keep iredescent sharks in an aquarium due to their large size and nervous nature but this isn't true as I have proved. I wonder if there is a way to tell before purchase instead of learnign the hard way.

In most cases I believe "stunting" is not a good thing. Usually it is a result from poor water conditions, poor diet, stress etc. I would never purposely keep any fish in a small tank on the assumption that it would grow to the size of its environment. I have heard many more stories about fish outgrowing an aquarium then I have stories about a fish staying small and remaining healthy. Most fish are indeterminate growers; they don't stop growing if given the chance. If you're taking proper care of a fish it's growth shouldn't be altered much. It just doesn't make sense. With that said I do believe captive fish generally won't reach the size wild fish do. Perhaps it is the ever present nitrates or the limited diet or whatever but I believe you can have a healthy fish smaller then typical specimens. I would consider a LMB for example that never grew past 6" unhealthy and stunted but if it were to reach 18" and stop I don't think there would be a problem with that fish despite the fact they can get larger.
To sum it up I believe that the real wives tale here is that fish don't outgrow their aquariums, in many cases they do. When stunted it is typically a result of poor care but on occasion you encounter smaller then normal fish. Most keepers though IME do believe a fish won't outgrow its tank and I believe it is a dangerous assumption. Stock fish in a tank appropriate to the size they are supposed to reach. If they don't then they don't but it is best to remain prepared.

In most cases I believe "stunting" is not a good thing. Usually it is a result from poor water conditions, poor diet, stress etc. I would never purposely keep any fish in a small tank on the assumption that it would grow to the size of its environment. I have heard many more stories about fish outgrowing an aquarium then I have stories about a fish staying small and remaining healthy. Most fish are indeterminate growers; they don't stop growing if given the chance. If you're taking proper care of a fish it's growth shouldn't be altered much. It just doesn't make sense. With that said I do believe captive fish generally won't reach the size wild fish do. Perhaps it is the ever present nitrates or the limited diet or whatever but I believe you can have a healthy fish smaller then typical specimens. I would consider a LMB for example that never grew past 6" unhealthy and stunted but if it were to reach 18" and stop I don't think there would be a problem with that fish despite the fact they can get larger.
To sum it up I believe that the real wives tale here is that fish don't outgrow their aquariums, in many cases they do. When stunted it is typically a result of poor care but on occasion you encounter smaller then normal fish. Most keepers though IME do believe a fish won't outgrow its tank and I believe it is a dangerous assumption. Stock fish in a tank appropriate to the size they are supposed to reach. If they don't then they don't but it is best to remain prepared.

I disagree, the fish I have stuinted were fed primarily live food, daphnia magna, black worms, mosquito larvae and premium fish food, not pet shop food. A 10 or 12 inch fish that should have grown to a meter should have grown much larger under these conditions. Especially since he was summered in a large pond. some fish seem to grow no matter what others don't but bad food and bad water conditions are not the problem in all cases especially the ones I have experimented with. I suspect the irredescent i had was some sort of sport that was accedentally bred since these fish are bred by the millions for food it maybe possible but not all the fish i seen this happen with could have had this problem. Shovelnose sturgeon even when kept in large tanks do not even approch the maximum size. One other thing you should remember Not all fish ever reach the maximum possible size. Just because the world record is four feet for a fish doesn't mean every individual will reach even close to that size. To many times we think all fish have the potintial to reach world record size. Shovelnose sturgeon have grown to 39 inches but are seldom seen in the wild more than 24". combine this with the effects of living in a tank, even a large one, the fish might not reach more thna 18" with out any health problems or real stunting.

I disagree, the fish I have stuinted were fed primarily live food, daphnia magna, black worms, mosquito larvae and premium fish food, not pet shop food. A 10 or 12 inch fish that should have grown to a meter should have grown much larger under these conditions. Especially since he was summered in a large pond. some fish seem to grow no matter what others don't but bad food and bad water conditions are not the problem in all cases especially the ones I have experimented with. I suspect the irredescent i had was some sort of sport that was accedentally bred since these fish are bred by the millions for food it maybe possible but not all the fish i seen this happen with could have had this problem. Shovelnose sturgeon even when kept in large tanks do not even approch the maximum size. One other thing you should remember Not all fish ever reach the maximum possible size. Just because the world record is four feet for a fish doesn't mean every individual will reach even close to that size. To many times we think all fish have the potintial to reach world record size. Shovelnose sturgeon have grown to 39 inches but are seldom seen in the wild more than 24". combine this with the effects of living in a tank, even a large one, the fish might not reach more thna 18" with out any health problems or real stunting.

OK that covered much of what I was going to write so no need for redundancy....

I disagree, the fish I have stuinted were fed primarily live food, daphnia magna, black worms, mosquito larvae and premium fish food, not pet shop food. A 10 or 12 inch fish that should have grown to a meter should have grown much larger under these conditions. Especially since he was summered in a large pond.

How long did you have the fish and what would you consider the normal growth rate for an iridescent shark? The fish didn't just stop growing due to some internal sensor telling it the habitat it was in was too small. There must have been some other factor involved. I don't know the specifics of your setups I cannot give an answer.

some fish seem to grow no matter what others don't but bad food and bad water conditions are not the problem in all cases especially the ones I have experimented with. I suspect the irredescent i had was some sort of sport that was accedentally bred since these fish are bred by the millions for food it maybe possible but not all the fish i seen this happen with could have had this problem. Shovelnose sturgeon even when kept in large tanks do not even approch the maximum size. One other thing you should remember Not all fish ever reach the maximum possible size. Just because the world record is four feet for a fish doesn't mean every individual will reach even close to that size. To many times we think all fish have the potintial to reach world record size. Shovelnose sturgeon have grown to 39 inches but are seldom seen in the wild more than 24". combine this with the effects of living in a tank, even a large one, the fish might not reach more thna 18" with out any health problems or real stunting.

I already addressed all of this. I clearly stated that I believe aquarium fish are typically smaller then their wild counterparts.

Behold

I do believe captive fish generally won't reach the size wild fish do. Perhaps it is the ever present nitrates or the limited diet or whatever but I believe you can have a healthy fish smaller then typical specimens. I would consider a LMB for example that never grew past 6" unhealthy and stunted but if it were to reach 18" and stop I don't think there would be a problem with that fish despite the fact they can get larger.

However just because some individuals will remain smaller then normal I don't think that is justification for improper stocking. I would never suggest getting fish you cannot properly house because it might remain smaller then average. I'm aware that largemouth bass can reach nearly three feet. Do I think mine will? No, but I do believe it will reach an average size for the species so I would stock in accordance to that. If it remains smaller through no fault of my own so be it. With that said I can list dozens upon dozens of cases where a fish did outgrow its tank because the owner thought it would remain small and stocked it in an improper setup.

Edited by sandtiger, 08 March 2008 - 11:52 PM.

How long did you have the fish and what would you consider the normal growth rate for an iridescent shark? The fish didn't just stop growing due to some internal sensor telling it the habitat it was in was too small. There must have been some other factor involved. I don't know the specifics of your setups I cannot give an answer.

I had the fish for 7 years

I already addressed all of this. I clearly stated that I believe aquarium fish are typically smaller then their wild counterparts.

Behold
However just because some individuals will remain smaller then normal I don't think that is justification for improper stocking. We know that an oscar for example can reach 12-18" so we stock it according to that. Just because the fish might only reach 9" doesn't mean we should stock it in a smaller tank.

A fish doesn't care how big it gets, just that it has plenty of good food, good water and and a reletivly interesting environment. planning a tank on how big a fish can get would put an end to 90% of the hobby. so many of our aquarium fish have the potintinal to grow much larger than they ever do in an aquarium. a great many of our aquarium fish attain a size two or three times as big in the wild as they do in an aquarium.

I think you started this thread to be provocative but I'll indulge you.

I've had plenty of fish get larger than any books said they would, and larger than I've ever witnessed in the wild.

I guess my nexg question is why has this be promoted by so many people?

I really did give you the answer to this early on.. Ethics and Animal welfare which is exactly where this thread is now going...

I think you started this thread to be provocative but I'll indulge you.

I've had plenty of fish get larger than any books said they would, and larger than I've ever witnessed in the wild.

This is very true as well..some fish in captivity will far exceed the size that is average in the wild....

I think you started this thread to be provocative but I'll indulge you.

If I wanted to be provocative i could do much better than that

I've had plenty of fish get larger than any books said they would, and larger than I've ever witnessed in the wild.

What would that prove in relation to what I have experienced nad has b een discussed here? We have already established some fish seem to have no growth limits, pacu come to mind, and others do, goldfish would be the best example.

I think you started this thread to be provocative but I'll indulge you.

I've had plenty of fish get larger than any books said they would, and larger than I've ever witnessed in the wild.

What fish? How big were they when you caught them? How long did you keep them? How big was the aquarium in relation to the fish? Aquarium books tend to give the size fish will attian in an aquarium.

A fish doesn't care how big it gets, just that it has plenty of good food, good water and and a reletivly interesting environment. planning a tank on how big a fish can get would put an end to 90% of the hobby. so many of our aquarium fish have the potintinal to grow much larger than they ever do in an aquarium. a great many of our aquarium fish attain a size two or three times as big in the wild as they do in an aquarium.

Fish may not care but it isn't like they can make a decision on it. In ideal conditions fish don't stop growing. I don't care if planning a tank on how big a fish can get puts an end to 90% of the hobby. Large growing fish don't belong in small tanks. If that makes people angry that thats to bad for them. There are plenty of smaller options that exist in the hobby.
And like teleost I have seen many aquarium specimens grow larger then wild counterparts. A constant food supply, longer then average life, lack of energy expenditure and a winter cooling period can all increase a captive fish's growth IMO.

I really did give you the answer to this early on.. Ethics and Animal welfare which is exactly where this thread is now going...

Don't you believe that if you're going to be keeping an animal it should be done so properly?

What fish?

various genus

How big were they when you caught them?

Usually very young

How long did you keep them?

Until death (various age) but not terribly longer than wild expectancy

How big was the aquarium in relation to the fish?

Usually 8:1 to 10:1

Aquarium books tend to give the size fish will attian in an aquarium.

I'm not speaking of aquarium books, I'm speaking of "fishes of" books for NA natives.