There is a groove on the back and another on the venter in front of the tail fin of this species, but there are no bony scutes on the sides. The first dorsal fin has six spines. The second dorsal fin has one spine and 25-27 connected soft rays, followed by a 2-rayed finlet. The anal fin consists of a single detached spine that is covered by skin in most specimens over 1 ft. (30 cm) long, followed by another spine with 16-18 connect soft rays and 2-rayed finlet.

It resembles the cobia (Rachycentron canadum) in shape, but can be distinguished by its coloration as well as the finlet after the dorsal and anal fins. The back is blue-green. On each side there is a broad, dark blue, horizontal stripe near the back and one or two narrower, light blue stripe(s) beneath the broader one. Between and around these blue stripes, the sides are a cadmium yellow. The belly is white or silver, often with a yellow or pink tint. The tail is yellow and the other fins are a greenish or olive yellow.

Fishing methods include trolling with small baits and lures or live bait fishing. The rainbow runner is sometimes caught on heavy tackle intended for larger fish, but its fighting ability is reduced when this happens. When hooked on light tackle, it is an excellent game fish and a tough fighter prone to fast surface runs.

It is an excellent food fish with firm white flesh. In Japan it is cooked with a special sauce or eaten raw and considered a delicacy.