Cichlids

Blue Discus - Symphysodon aequifasciata
Blue Discus - Symphysodon aequifasciata. Photo © Patrick Farrelly / Wikipedia.

Cichlids (Cichlidae) are a group of bony fishes that includes tilapia, angelfishes, discus, oscars, and peacock bass. Many species of cichlids are popular as pets and are kept in home aquariums. Cichlids are primarily freshwater fishes although they are some species that inhabit brackish and marine habitats.

Cichlids are diverse in terms of both species numbers and physical form. Generally, cichlids are medium sized fish that are somewhat laterally compressed.

Their body shape varies from species to species. Body shapes include oblong, tubular, elongated, or round (disk-like) forms. A number of cichlid genera—such as angelfishes, American cichlids, jewelfishes, and discus—are popular in the aquarium trade.

Scientists estimate that there are as many as 2000 species of cichlids alive today. These species are classified into about 140 subgroups. Cichlids are unique in that they have fused pharyngeal bones and unique musculature that enables them to use these bones as a second set of jaws. They have a single nostril on each side of their forehead and they lack a bony structure present in some other fish, beneath their eye. Their pharyngeal jaw and teeth, which are located in their throat, enable cichlids to take advantage of many specialized feeding strategies. Their two sets of teeth and jaws enable them to hang on to prey and crush them efficiently

Cichlids are herbivores that feed on aquatic plants, algae, and small invertebrates. Some species are detritivores that feed on organic material, while others are predators that eath other fishes and insects. Some cichlids specialize on a narrow diet while others are more generalist in nature, feeding on a variety of prey or vegetation.

 By specializing in their feeding habits, cichlids have diversified so they occupy many different niches.

Cichlids inhabit freshwater and occasionally brackish water in lowland, tropical and subtropical regions. The live in lakes and slow-moving rivers. Cichlids are highly endemic fishes. Their range includes East Africa, Madagascar, Asia, Sri Lanka, South America, Central America, and the Middle East. Cichlids are most diverse in Africa and South America. There are no cichlids that are native to Europe, Australia, and North America. Cichlids are not present on most oceanic islands, although they do inhabit Madagascar, Cuba, and Hispaniola.

Cichlids are, for fish, rather attentive parents. All species offer some extent of care to their young by protecting eggs and larvae and even looking after young fish for a period of time. They use a variety of brooding techniques including open brooding, cave brooding, and mouth brooding.

Classification

Cichlids are classified within the following taxonomic hierarchy:

Animals > Chordates > Vertebrates > Bony Fishes > Ray-Finned Fishes > Perciformes > Cichlidae

Cichlids are divided into the following taxonomic groups:

  • Astronotiane - Members of this group are native to South America, where they inhabit the Amazon River, Prana River, Orinoco River, and Paraguay River.
  • Cichlasomatinae - Members of this group are native to the Caribean, southern United States, Central America, and Mexico.
  • Cichlinae - Members of this group are native to South America.
  • Etroplinae - Members of this group are native to Shri Lanka, Madagascar, and India.
  • Geophaginae - Members of this group are native to South America and Central America.
  • Heterochromidinae - Members of this group are native to Central Africa where they inhabit the Congo River.
  • Pseudocrenilabrinae - Members of this group are native to the Middle East and Africa.
  • Ptychochrominae - Members of this group are native to Madagascar.
  • Retroculinae - Members of this group are native to South America.