Lizardfishes (order Aulopiformes) are generally deep water fish species (130-550 meters), although there are shallower water species. Their name comes from the Greek 'aulopias' which means pipe, due to the shape of their body.

With an elongated body and oval section, Lizardfishes have a large mouth that extends past the eyes. The dorsal fin has 14-16 rays and is located in the anterior third of the body. They have a reduced dorsal adipose fin located at the level of the middle of the anal fin. The pectoral fins have 13 rays and arise just below the lateral line and in a slightly anterior position than the dorsal and pelvic fins. The pelvic fins are larger than the pectoral fins, have 9 rays and are located in an abdominal position. The anal fin has 10-13 rays. None of the fins have spines.

Another characteristic of Lizardfishes, although not unique to this order of fishes, is that they either have a very poorly developed swim bladder, or even a completely absent swim bladder in their anatomy.

Lizardfishes are predators that feed on small fish and shrimp. There is sexual dimorphism, mainly the colors of the dorsal, anal and pelvic fins. As a curiosity of this order of species, some species of Lizardfishes are hermaphrodites, being self-fertilization possible. There are currently a total of 261 described species, classified into 15 families and 47 genera.