Nerita melanotragus, common name black nerite, is a medium-sized sea snail, a marine gastropod mollusc in the family Neritidae, the nerites.

This may be a method of thermoregulation, because if N. melanotragus is on a horizontal surface, it would absorb the maximum solar radiation, whereas on sloped or vertical surfaces it absorbs less energy (and thus heat).

[3] The shell is of moderate size, very solid, globose-oval, and smooth except for weak shallowly incised spiral lines.

The operculum is granular, pinkish-lilac, with two spiral bands of black.

An almost complete sequence of the mitochondrial DNA of this species was analyzed by Castro & Colgan (2010).