[Bob]

Externally, cichlids can be identified by a suite of characters including single nostril, usually divided flank lateral line, 16 (exceptionally 14) principal caudal fin rays, and the spines in the dorsal, anal and pelvic fins. 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. There are examples of rheophilic to extreme lentic forms; and herbivorous, planktivorous, molluscivorous and piscivorous specialists have been distinguished, although the majority of the South American cichlids may be opportunistic carnivores. Cichlids have a varied behavior and are established study objects of ethologists.