Cichlids are among the most species-rich and diverse families of freshwater fishes, with a range in the Eastern Hemisphere extending throughout Africa and parts of the Middle East, including Madagascar, Sri Lanka, and along the southern coast of India. In the Western Hemisphere, cichlids occur from southern Texas to Argentina. Within the Perciformes, cichlids are placed in the suborder Labroidei, a large assemblage containing over 1800 species, or 5-10% of all living fishes. Members of this suborder possess highly derived pharyngeal jaws, a configuration referred to as the “labroid pharyngeal jaw”. Recent research suggests that the labroid pharyngeal jaw had important evolutionary consequences that have prompted significant diversification within the group, as it has allowed for development of diverse trophic behavior (for examples see:Greenwood 1978, Liem 1986, Gobalet 1989, Liem 1991).
Life history and other ecological attributes vary greatly among cichlids across their global range. In the Neotropics alone, studies have revealed a great diversity in cichlid ecology, morphology and behavior (Lowe-McConnell 1991, Winemiller et al.1995). This great diversity, in addition to providing evidence of rapid evolution, is the reason why cichlids provide a valuable resource for studies of speciation and adaptive radiation (Meyer 1987, Farias et al. 1999).