They should be in groups of 3 or more, as they are a schooling fish. There is always one dominant one, the leader of the group, who is usually the biggest. His stripes will turn a lighter shade of grey while the smaller more submissive ones will have jet black stripes. the big one will often chase the small ones to put them in their place, but never does any harm. They are very susceptible to ich as they are a scaleless fish. They prefer water that is a bit cooler and more aerated/oxygenated. They will usually eat sinking pellets; I feed mine with sinking shrimp pellets, frozen brine shrimp, and the occasional flake. They usually won't venture to the top for the flakes, only eating it if it falls past the others, unnoticed. They grow to about 14" in captivity and can live for over 10 years, although there are some housed in public aquaria that are up to 28" and over 50 years old. They are very peaceful and won't hurt any other fish, however you shouldn't keep them with fish that are very aggressive, unless they are much larger. They are a wonderful, active and outgoing fish, and a pleasure to keep in the home aquarium.