Crestfish, also called unicornfish, are a small family (Lophotidae) of deepwater, marine bony fish in the order Lampridiformes. These rare fish have unusual boxlike heads with protruding foreheads and ribbon-shaped silvery bodies with crimson fins. The prominent dorsal fin extends from the tip of the head to beyond the tail; the first rays of this fin form a crest above the head, giving these fish their common name. Crestfish also have a short anal fin, but the pelvic fin is absent. At least one species of crestfish (Lophotus capellei) has no scales, and another species (L. lacepede) has tiny, cycloid scales that are easily rubbed off.
Some crestfish can be quite large. Specimens as large as 6 ft (1.8 m) long have been found off the coast of southern California, although smaller fish (about 3.5 ft/1 m) are more typical. Crestfish are related to ribbon-fish (family Trachipteridae) and oarfish (family Regalecidae), but are distinguished from these related families by having high foreheads and anal fins.
See also Opah.