Myth or Fact??

[jpappy789]

Genetics are something that rarely enters this discussion. In any given brood, there are bound to be outliers on both ends of the size spectrum. Not all fish have the genetic potential to reach the largest size a given species is capable of. I have read about not only discus, but a variety of livebearers releasing growth inhibiting hormones, but am too lazy to dig up any links atm. Also, I think it's more a function of reducing competition for food than it is about controlling size to fit the surroundings.

I agree, I think the hormone discussion was not about limiting the size of the fish that releases them.

 

[DrgRcr]

Just my .02 here, but I have 2 groups of fry/juvies, same species, born at the same time, growing out. One group in a standard 20g, one in a 10g. The group in the 20 are about 30% bigger than the ones in the 10, probably 3-4 weeks worth of growth. They are all getting moved to a 4' 33 long. It will be interesting to see if the smaller ones "catch up". Scientific evidence or not, I believe tank size definately has had some role in it. And I do 50% WC's every 3 days with rock solid parameters.

 

[Leginess]

If it has more room to grow it will grow larger.
But only to it's max size.
In a smaller tank if the fish is cramped it may stunt it's growth.
IMO

:iagree:

 

[dundadundun]

i'm a big guy that sleeps in a small room... false. :uhoh:

 

[J double R]

Just my .02 here, but I have 2 groups of fry/juvies, same species, born at the same time, growing out. One group in a standard 20g, one in a 10g. The group in the 20 are about 30% bigger than the ones in the 10, probably 3-4 weeks worth of growth. They are all getting moved to a 4' 33 long. It will be interesting to see if the smaller ones "catch up". Scientific evidence or not, I believe tank size definately has had some role in it. And I do 50% WC's every 3 days with rock solid parameters.

define "rock solid parameters".

A couple things here that can scientifically explain the size difference in your fish. Given that you are changing 50% of the water in both tanks, with fish of the same age, the concentration of TDS (not just nitrates, but hormones and other things that normally are never measured) is always going to be higher in the tank with less volume, which is a dead on indicator that those fish are going to grow slower and stay smaller.

Unless you start changing the water in a ratio that brings the TDS concentrations to an EQUAL amount(not percentage) vs. the larger volume tank, those fish will likely never catch up.

 

[SubRosa]

Total excrement. In high school we did an experiment where we set up 2 10 gal tanks. In each tank was placed a 1" baby Oscar. Each fish was fed the same amount, weighed out to 4 decimal places on a Mettler balance. Tank #1 was topped off as needed but no water changes were performed. Tank #2 received a 25 % weekly change. The experiment ran 3 months. At the end of the experiment the fish in tank #1 had hardly grown. The fish in tank #2 had doubled in size. There is no way that a fish looks around and thinks "those walls are getting awfully close, I'd better stop growing!" As stated earlier a build up of waste and metabolic byproducts is responsible for the illusion that fish grow to the size of their environment.

 

[thebrandon]

False. A fish will out grow its tank if the water is kept pristine. It's been done by plenty of people. The usual show is a 5g tank with a 55g or bigger sump and frequent water changes. Eventually the goldfish, oscar, other monster etc. though morphologically healthy, gets too big for the tank to the point of rubbing the walls head-to-tail.

Just imagine a fish in a lake. If you put a wire frame around the fish but leave it in the lake and the water still flows freely through the cage, the fish will still grow as if it were in the lake. The stress of the cage is another story, but a fish will easily outgrow its container if it is a large species and water quality is actually maintained.

This pretty much nailed it

 

[cichlidcichlid]

I agree with what was already stated above. If you have a constant flow of fresh water you will have better growth. However, aside from the hormone argument, I think there is stuff in the water that isn't usually tested that would inhibit growth.

It is still possible that there is some sort of hormone limiting growth because in the test you mention above, they had a constant flow of fresh water. Meaning that any hormone would be quickly disposed of rather than being dispersed and influencing a fishes growth.

Aside from the fact that this could be done the fish would most likely pick up some disease from being consistently stressed.

I find this topic very intriguing because I don't think it is really fully understood.