gammerus

When my brother brought over his fish one of them decided she couldn't wait and gave birth on the way over. So for a little over a month now I have had half a dozen fry in my one gallon tank. There is no filtration so I just do water changes everyday. The 3 fry that disapeared into the 40gal have allmost tripled in size now. I cannot figure out why, the water temperature in the tanks is identical, the water is from the same source. What do I do?

Stradius011

It is because the ones in the 40 gallon have more room to grow.