The whitefin trevally (Carangoides equula), also known as the horse trevally, is a species of deep water offshore fish in the jack family Carangidae. The species inhabits the tropical to temperate waters of the Indo-Pacific and central Pacific, ranging from South Africa in the west to Hawaii in the east. The whitefin trevally is a moderate-sized fish, growing to 37 cm, and is distinguished by a number of morphological traits, including fin size, gill raker count, and colour. It inhabits the continental shelf and slope at depths to 200 m over sand and mud substrates, where it preys on fish, crustaceans, and cephalopods. Studies in Japan indicate a length at sexual maturity of 17.4 cm on average, with spawning occurring between May and October, with each individual spawning multiple times. Whitefin trevallies are of high importance to fisheries in Japan, where they are taken by trawlers, although the catch numbers have halved since the 1980s. It is of minor importance elsewhere throughout its range, but is considered a good table fish. Taxonomy and naming The whitefin trevally is classified within the genus Carangoides, a group of fish commonly known as jacks and trevallies. Carangoides falls into the jack and horse mackerel family Carangidae, the Carangidae are part of the order Carangiformes. The species was first scientifically described by Dutch naturalists Coenraad Jacob Temminck and Hermann Schlegel in 1844 based on a specimen taken from the waters off Japan, which was designated to be the holotype. They named the species Caranx equula, although the species was later moved to Carangoides, as well as having a new genus created for it, Kaiwarinus. This genus is currently considered invalid, though a 1988 review of the phylogeny of the Carangidae found it to be valid, and to be the sister genus to Pseudocaranx, not closely related to Carangoides. The species was independently renamed as Carangoides acutus in 1974, but this is rejected as a junior synonym under ICZN nomenclature rules. Specimens taken from Hawaii and Easter Island in the Pacific Ocean initially had the name Caranx (Carangoides) dasson applied to them by the American ichthyologists Jordan and Snyder. This name was eventually synonymised with Carangoides equula, but uncertainty still remains whether this population actually represents a separate species or subspecies. The Carangoides dasson population has the same diagnostic features as Carangoides equula, but exhibit more slender bodies and larger eyes, with William Vaniz-Smith indicating