Males are mainly blue with yellow throats. Females grey/brown. They like alagae and the aufwuchs found within the biocover. When not enough algae are found, they will eat the plants you try to keep.
Several of the populations of M. fainzilberi have OB forms occuring along with a normal color pattern. Locations with documented OB forms include: Lupingu, Makonde, Lutara Reef, Njambe, Lundo Is., Thumbi Pt., Magunga, Tanzania; Lumbaulo, Mozambique; and Charo, Malawi. In general, OB males are quite rare. The OB males can vary dramatically, but all have a basic BLUE sheen and most usually have some remnants of their vertical bars, even if faint or broken-up. Juveniles have the normal female coloration until sexually mature. OB males and females do not aquire the black botches until at least 3 months old.