The species is the only member of the genus Elagatis, which was created 15 years after its initial description, and is closely related to the amberjacks.

The rainbow runner is easily distinguished by its body shape, and the brilliant colouration which gives the fish its name.

[3] The species was first scientifically described in 1825 by French zoologists Jean René Constant Quoy and Joseph Paul Gaimard based on the type specimen collected from the Indian Ocean, somewhere in the Malay Archipelago.

[7] Phylogenetically, the species is most closely related to the amberjack genus, Seriola, being the most basal member identified of the carangid tribe Naucratini.

[9] The rainbow runner has a subcylindrical, elongated to almost fusiform body, with a long, pointed head and snout and a tapering rear end before the caudal fin emerges.

In the Western Atlantic, the species occurs from Massachusetts and Bermuda to northeastern Brazil, including the northern and southern Gulf of Mexico, the Bahamas, and the Greater and Lesser Antilles,[12] extending east to at least the Azores.

[18] The species is primarily pelagic, inhabiting the upper 164 m of the water column,[19] sometimes close to land over rock and coral reef systems, as well as far offshore.

The species occasionally comes quite close to shore, known to inhabits lagoons for short periods,[20] and juveniles have even been reported in a Taiwanese estuary system.

[21] Rainbow runners, like other carangids such as yellowtail kingfish, are easily attracted to special fish-attracting devices (FADs), floating buoy-type structures.

The species has been shown to occupy a water zone outside of the FADs up to 12 m deep and 10 m wide, treating them as if they were stationary objects.

Rainbow runners may increase their swimming and prey-searching abilities rapidly with their growth, becoming more efficient at finding their preferred prey items.

The larval stages have been studied in detail, with the diagnostic features of the larvae include a supraoccupital crest and distinctive patterns of pigment and melanophores.

Their flesh is said to be of fair to excellent standard, depending on personal preferences, but generally fetch a low price at markets because they are relatively unknown.

Often, they are taken while trolling for other species such as tuna and mackerel, but are often targeted inshore by anglers on the west coast of the Americas using surface popper-style lures.

The species takes a wide variety of baits, including live and cut fish, squid, octopus, and probably other crustaceans resembling their natural food.