The Black Molly is an all-black, short-finned hybrid variation of Sailfin Molly. Though they might have patches of silver or gold when young, they will outgrow this with age. You can differentiate the male from the female by looking for a pointed or rounded anal fin. If the anal fin is round, then it is female. Males also have larger dorsal fins, while females have a pregnancy spot.
This fish can adapt to various salt levels in the aquarium. In fact, with gradual acclimation, you can maintain the fish in either a saltwater or freshwater aquarium. If you choose to keep them in freshwater conditions, add a teaspoon of salt per gallon to keep them healthy. Also, ensure you have planted the aquarium as densely as possible. Having floating plants in the corners will help promote rearing outside the breeding tank.