"I" below should read "we" since my 9 yo daughter started this all in June when she won the class crayfish and needed a better-than-a-bucket house. I've caught the bug, too, because I have a degree in Biology without an outlet!
I have a 10 gal
fresh water tank (just added a heater, 78, degrees, air stone) that currently holds 1 crayfish, 1 large, female, apple snail, a pleco and 2 zebra danios. The crayfish has eaten: 1 large pleco, 2 goldfish, 4 danios. The crayfish we have now is a replacement for the first one; it escaped and we never found it! You'd think it would have stunk after a few days. The snail has laid about 15 clutches since 6/12k, I currently have 1 in the breeder tank and 5 more inside the lid of the main tank, and I want to try to hatch them (gave some to the pet store and they haven't been able to hatch them). I also have an 8 gallon tank, rudimentary (no heater but the light seems to keep it at about 72 deg) or air stone), that will be dedicated to the snails. I have a clutch in that one, sitting on some sphagnum moss, a bit wet on the bottom. Both tanks are pretty humid.
Hoping to get some good advice, and hear about failures, on hatching these guys!