Opah, a colorful marine fish found in open waters. Although not abundant, opahs are found in almost all seas. Opahs range in length from about 3 to 6 feet (.9 to 1.8 m) and weigh from 50 to 400 pounds (23 to 180 kg) or more. The body is oval and compressed from side to side. Opahs are grayish above shading to rose underneath, and are marked with white spots. The jaws, fins, and tail are red and the eyes are ringed with gold. The flesh, which is considered excellent food, is also red.

The opah is sometimes also called moonfish.

The opah is Lampris regius, the only member of the family Lamprididae, or Lampridae.