Cichlids are fish from the family Cichlidae in the order Cichliformes. This family is both large and diverse. At least 1,650 species have been scientifically described, making it one of the largest vertebrates families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.

Since 1945, cichlids have become increasingly popular as aquarium fish.

The most common species in hobbyist aquaria is Pterophyllum scalare from the Amazon River basin in tropical South America, known in the trade as the “angelfish”. Other popular or readily available species include the oscar (Astronotus ocellatus), convict cichlid (Archocentrus nigrofasciatus) and discus fish (Symphysodon).