I have kept and bred them in the past. They do fine in freshwater. They eat only live food, mainly feeder guppies (or gambusia). The males are smaller than the females, and can get eaten. You have to watch for the fry, as they also will be eaten after a day or so. The fry are a pain as they too require live food, which is mostly guppy fry. Mine did ok including reproducing in a 20gal long, though I think a longer tank would be better. They are cool, but will eat anything else in the tank.