Ocosia is a genus of ray-finned fishes, waspfishes belonging to the subfamily Tetraroginae, which is classified as part of the family Scorpaenidae, the scorpionfishes and their relatives.

Ocosia was originally described as a monotypic genus in 1904 by the American ichthyologists David Starr Jordan and Edwin Chapin Starks when they were describing Ocosia vespa as a new species with its type locality given as Sagami Bay in Japan.

[3] The genus name Ocosia is a latinisation of the Japanese word for venomous fishes in the Scorpaeniformes, okoze.

[4] There are currently 9 recognized species in this genus:[3] Ocosia waspfishes are characterised by having naked bodies with scales being largely absent.

[6] These are small fishes and the largest species, O. ramaraoi reaches a maximum standard length of 8.2 cm (3.2 in).