Does size really matter?

I did a mass spawning of Zebra Danio (7 males to 4 females) some time back in a 2ft tank. As soon as the fry became free swimming, I moved about 2 thirds of them to a 5ft tank.

All those remaining in the 2 ft tank are now double the size of any of those in the 5ft tank and also fewer survived in the 5ft than in the 2 ft....

So, if I have do draw a conclussion here, I'd say fish do not necessarily grow better in a bigger aquarium, which is quite the opposite to what everyone else says. Is this true, or what explains.??

 

Size does matter.......................
Oh sorry wrong forum.............

P.S.
I had the same experience.Smaller tank,faster growth.
BUT,the smaller tank had warmer water.
I also think that it may be that the fry do not need to search for food as much as in the bigger tank.

 

In a sense, you've performed an experiment. The question is: did you keep factors constant, execpt the tank size?

You've kept the species constant, and the fry come from the same breeding stock, so gentically most (although not all) should attain similar adult sizes. From there, you need to have the same water change schedule, filtration, water parameters (especially temperature), food and feeding schedule lighting, tankmates (if any), ratio of fish to water, current, any probably a few other factors I can't think of. Everything I've mentioned affects the growth rates and eventual size of the fish in question.

 

I think the fact that the one is smaller means that higher concentrations/effects are happening in the smaller tank than the bigger... i.e

Food is a bit more in the smaller tank than the bigger.
Food is easier to find
Filtration may be better.
Temperature may be different
You possbly doing more % water change on the smaller because it's easier.