''Lamprologus lethops'' is a species of cichlid fish from areas with fast current in the

Congo River The Congo River ( kg, Nzâdi Kôngo, french: Fleuve Congo, pt, Rio Congo), formerly also known as the Zaire River, is the second longest river in Africa, shorter only than the Nile, as well as the second largest river in the world by discharge ...

in Central Africa, where it is believed to live in depths as great as or below the surface. It reaches up to about in standard length, with females being somewhat smaller than males, is all whitish in color (non- pigmented), and essentially blind as adult, as their eyes are covered in a thick layer of skin (only retain a slight sensibility to light). This is entirely unique among cichlids and an adaption to the perpetual darkness of its habitat, similar to the adaptions seen in

cavefish Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish and ...

. The eyes of juveniles are rudimentary and not covered by skin. ''L. lethops'' is almost only known from the mainstream of the lower Congo River in the vicinity of Bulu; however very small numbers have been found up to upstream or downstream from this site. The relatively high number of ''L. lethops'' that have been found at Bulu is likely due to the unique features at this site, where fast currents go from deep parts of the river to the upper parts. These may on occasion "catch" a deep water fish and force it up, also resulting in gas-bubble disease due to the rapid change in pressure. Consequently, when found at the surface they are usually already dead or die within minutes, although a minority may be saved by a special method where a needle is used to reduce the internal pressure. Very small numbers have subsequently been kept in aquaria. Based on these, its behavior is essentially similar to that of its "normal-looking" relatives, like '' L. congoensis''. They have laid eggs in aquaria, which however did not hatch. Among other fish species with similar adaptations (reduced eyes and non-pigmented) found in similar habitats in the Congo River are an elephantfish ('' Stomatorhinus microps''), a clariid catfish ('' Gymnallabes nops''), a mochokid catfish (''

Chiloglanis ''Chiloglanis'' is a genus of upside-down catfishes native to Africa. These species have modified lips and barbels that form a suckermouth. They also have a naked (scaleless) body. Sexual dimorphism has been reported in ''Chiloglanis''. The adul ...

'' sp.), two

claroteid catfish The Claroteidae are a family of catfish (order Siluriformes) found in Africa. This family was separated from Bagridae. However, the monophyly of the family is sometimes contested. The 12 genera contain 86 known species of claroteids in two subfa ...

('' Notoglanidium pallidum'' and '' Platyallabes tihoni''), and four spiny eels (''

Mastacembelus aviceps ''Mastacembelus'' is a genus of many species of spiny eel fish from the family Mastacembelidae. They are native to Africa (c. 45 species) and Asia (c. 15 species). Most are found in rivers and associated systems (even in rapids), but there are ...

'', '' M. brichardi'', '' M. crassus'' and '' M. latens''). The closely related '' Lamprologus tigripictilis'' lives in shallow water in the exact same region as ''L. lethops'', but it has normal pigmentation and eyes.

References

{{Taxonbar, from=Q6425310 lethops Fauna of Central Africa Taxa named by Tyson R. Roberts Taxa named by Donald J. Stewart Fish described in 1976 Endemic fauna of the Democratic Republic of the Congo