I just got back from being out of town for a month. Right before I left, two fo the mollies in my 55 gallon had fry, so I moved at least 70 of them into my fry tank. I thought that there couldn't be too many left in the 55 gallon. When I got back from being away for a month, there were at least 10 fry from the same batch as half of the fry in the 55 gallon. Plus there were at least 20 other fry in there, even some guppies. I have a lot of plants in my tank. Live floating plants, a whole bunch of silk plants and a big patch of breeder grass at the bottom. I also use glass marbles which are a GREAT place for the fry to hide. I can't even find them in there.