Nearly all of them live their entire life in freshwater. Only a few species frequent brackish water. Sizes range from ca 30 mm to at least 600 mm among South American species. Habitat and food specializations are still largely uninvestigated, although it seems that the spectrum is considerable.
Cichlids have a varied behaviour and are established study objects of ethologists.
Reproductive behaviour includes mouth brooding, of which several strategies are recorded, although the majority of the American cichlids are substrate spawners. All cichlids practise some form of parental care. South America has at least 420 species of cichlids. Cichlids are a proportionally more important faunal component numerically in Africa and Central America, but are nevertheless the major non-otophysan group in South America and one of the four largest families, the Characidae, Pimelodidae and Loricariidae having more or about the same number of species. Economically, only the Cichla species are important in fishery statistics.