I keep black mollies. Friendly fish! If you have a (one) male, they (all) will reproduce like crazy! They prefer warmer waters (78-82F). Succeptible to fungii, but for the most part, if you keep the water quality up, they are happy as can be. They aren't very demanding at all. They get stressed by agression, so keep calm, but lively tank mates. They will also skim your surface of the protein layer (they shiny, oily layer you sometimes see). They also eat green algae when not too well fed. These guys will eat 10 times a day if you feed them that often. Don't be suckered by their "I'm hungry" look.