The ''Rouleina maderensis'', also called the Madeiran smooth-head, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of fish in the family

Alepocephalidae Slickheads, also known as nakedheads or smoothheads, are deep water fishes that belong to the family Alepocephalidae. They are most commonly found in the bathypelagic layer, which is approximately 3000m below the surface. They get their name from ...

. It is found worldwide. This species reaches a length of .

References

*Markle, D.F. and J.-C. Quéro, 1984. Alepocephalidae (including Bathylaconidae, Bathyprionidae). p. 228-253. In P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese (eds.) Fishes of the North-eastern Atlantic and the Mediterranean. UNESCO, Paris. Vol. 1. ( Alepocephalidae Taxa named by Günther Maul Fish described in 1948 {{Rayfinned-fish-stub