The family Cichlidae is a diverse group of freshwater fishes, distinguished by complex behaviors and unique anatomical features, such as a specialized second set of pharyngeal jaws. With over 1,700 scientifically described species and total estimates reaching close to 3,000, cichlids are considered one of the most species-rich vertebrate families on Earth. They exhibit a wide range of sizes, shapes, and colors, reflecting their varied feeding strategies and adaptability.
Continental Distribution: Africa and the Americas
The global distribution of cichlids is concentrated in two major, geographically separated centers of diversity: Africa and the Americas. These regions account for the vast majority of species, categorized as “Old World” and “New World” cichlids, respectively. Africa is home to the largest number of species, with estimates suggesting at least 1,600 species originate there.
Cichlids generally inhabit warm, freshwater environments, including everything from fast-flowing streams and quiet rivers to vast, isolated lakes and temporary swamps. In Africa, the distribution extends across the continent, with some species also found in Madagascar and parts of the Middle East. The New World distribution spans from Central America, reaching as far north as the Rio Grande in southern Texas, down through South America to Argentina.
The environments occupied by cichlids vary significantly between the continents, influencing their physical and behavioral adaptations. African cichlids are predominant in large, ancient lakes, whereas New World species are more often associated with major river drainages.
The African Great Rift Lakes
The most spectacular concentration of cichlid diversity occurs in the East African Great Rift Valley. The three largest lakes—Tanganyika, Malawi, and Victoria—are home to massive “species flocks,” where a single ancestral lineage has exploded into hundreds of unique species. Over 95% of the fish fauna in these lakes belong to the Cichlidae family, making the region an unparalleled natural laboratory for evolutionary biology.
Lake Malawi alone contains over 1,000 endemic species, many of which are rock-dwelling cichlids collectively known as Mbuna. These fish have evolved specialized mouth and tooth structures to scrape algae from rocks, allowing hundreds of species to coexist by exploiting very specific ecological niches. Other species in Malawi include the predatory Haplochromis and the colorful Peacock cichlids, which occupy open-water or sandy habitats.
Lake Tanganyika, the deepest and oldest of the Rift Lakes, also hosts immense diversity, with famous genera like Tropheus and the Lamprologines. Tropheus species are generally herbivorous mouthbrooders. Lamprologines include rock-dwellers and unique shell-dwelling cichlids that use empty snail shells for protection and breeding. The unique water chemistry (high alkalinity and mineral content) and physical isolation of these systems promoted rapid speciation.
New World Habitats: Central and South America
Cichlids of the Western Hemisphere are distributed across a wide range of aquatic environments, with the greatest concentration of species found in the major river systems of South America. The Amazon, Orinoco, and Paraná river basins are the primary centers of diversity for these New World cichlids. Unlike the hard, alkaline water of the Rift Lakes, many South American cichlids thrive in softer, more acidic “blackwater” or “whitewater” conditions, with pH values often ranging between 6.5 and 7.4.
Iconic species such as the Angelfish (Pterophyllum species), Discus (Symphysodon species), and the robust Oscar (Astronotus ocellatus) all originate from these expansive South American river systems. These fish exhibit diverse body shapes and feeding habits, reflecting their adaptation to varied riverine habitats, including flooded forests and slow-moving tributaries. Many New World species are substrate spawners, laying eggs on submerged logs or rocks, and are known for their intensive biparental care.
In Central America, cichlids are found in numerous smaller lakes and river drainages, extending north into Mexico. These cichlids, often referred to as Cichlasomines, frequently inhabit waters that are harder and more alkaline than their South American counterparts, with pH values sometimes exceeding 7.6. Species like the Firemouth and Jack Dempsey are examples of the colorful and territorial cichlids that have adapted to the specific geological conditions of this region.