Synodontis is a large genus of African catfish in the family Mochokidae, the squeaker catfishes, found across much of the continent from the Nile and Congo basins to the Zambezi and the great East African lakes. The atlas's records span the Democratic Republic of the Congo, the Republic of the Congo, Cameroon, Tanzania, Burundi, Zambia, Benin, and Mali. The genus is instantly recognizable by its branched or feathery maxillary barbels, a mobile spine at the rear of the gill cover that the fish rubs against its pectoral spine to produce an audible squeaking sound (the source of the common name), and -- in several species -- a habit of swimming upside-down for extended periods, most famously in Synodontis nigriventris. The atlas covers 21 species with a broad adult size range, from about 2 in dwarf forms up to 21.5 in in the largest species.
Synodontis is one of the most popular African catfish genera in the aquarium hobby, prized for its combination of hardiness, striking barbels and patterning, and genuinely unusual behavior. The dwarf Lake Tanganyika species -- S. petricola, S. lucipinnis, and S. multipunctatus among them -- are hobby staples, and S. multipunctatus, the cuckoo catfish, is famous for a remarkable brood-parasitic strategy: it sheds its own eggs among the eggs of a mouthbrooding cichlid during spawning, and its fast-hatching fry consume the cichlid's eggs and young inside the host's mouth before the unwitting cichlid parent eventually releases them. Five species in the atlas's Synodontis coverage carry CARES conservation-priority status, and while most assessed species sit at Least Concern, a sizeable share of the genus has not yet been formally evaluated.