Ophidiiformes is an order of ray-finned fish that includes the cusk-eels, pearlfishes, viviparous brotulas, and others. Members of this order have small heads and long slender bodies. They have either smooth scales or no scales, a long dorsal fin and an anal fin that typically runs into the caudal fin. They mostly come from the tropics and subtropics, and live in both freshwater and marine habitats, including abyssal depths. They have adopted a range of feeding methods and lifestyles, including parasitism. The majority are egg-laying, but some are viviparous.
The viviparous brotulas form a family, the Bythitidae, of ophidiiform fishes. They are known as viviparous brotulas as they generally bear live young, although there are indications that some species do not. They are generally infrequently seen, somewhat tadpole-like in overall shape and mostly about 5–10 cm (2–4 in) in length, but some species grow far larger and may surpass 60 cm (2 ft).
Saccogaster is a genus of viviparous brotulas. They are found in the western Atlantic and Indo-Pacific.
The worm pearlfish is an eel-like fish in the family Carapidae.
Bellottia is a genus of viviparous brotulas which is found in the subtropical waters of the North Atlantic, the Mediterranean Sea and the Indo-Pacific.
Hephthocara is a small genus of Indo-Pacific viviparous brotula.
Eurypleuron is a genus of pearlfishes, with these currently recognized species:
Onuxodon is an Indo-Pacific genus of pearlfishes from the family Carapidae. The generic name is derived from the Greek onyx meaning "claw" and odon meaning "tooth", referring to the sharp fang like teeth of Onuxodon parvibrachium. Species in this genus are distributed from South Africa to Hawaii. They live commensally with molluscs. The three currently recognized species are:
Pyramodon is a genus of pearlfishes, with these currently recognized species:
Otophidium is a genus of cusk-eels, part of the subfamily Ophidiinae in the family Ophidiidae. They are found in the western Atlantic and eastern Pacific.
Parophidion is a genus of cusk-eels found in the Atlantic Ocean and the Mediterranean Sea.
The faceless cusk is a species of cusk-eel found in the Indian and Pacific Oceans at depths from 3,935 to 5,100 m. This species grows to 28.5 cm (11.2 in) in standard length, and is the only known member of its genus.
Bidenichthys capensis, the freetail brotula, is an uncommon South African fish of the family Bythitidae, and one of three species, and the type species, of the genus Bidenichthys. The species is found in intertidal zones and rocky tidepools ranging from East London to the Cape of Good Hope, South Africa. It grows up to 90 mm long TL.
Brotula barbata, commonly known as the goatsbeard brotula, is a species of cusk-eel in the genus Brotula. It lives in the Indo-Pacific, in depths of up to 300 meters. It is dark brown with a submarginal black band and narrow white border on the dorsal and anal fins versus greenish to orange brown with orange-bordered dorsal and anal fins, and it grows up to be around 100 centimeters. It has a carnivorous diet, and it is oviparous.
Brosmophycinae is a subfamily of the viviparous brotulas. They are divided from the subfamily Bythitinae by having the dorsal fin, caudal fin and anal fin all separate whereas they are joined in the Bythitinae. It is divided into the tribes Dinematichthyini and Brosmophycini, with the first having hardened genital claspers and the second soft genital claspers. A review in 2016 elevated the Dinematichthyini to the status of a family the Dinematichthyidae.
Bythitinae is a subfamily of viviparous brotulas, one of the two subfamilies in the family Bythitidae. This subfamily is characterised by having the dorsal, caudal and anal fins combined. They are mostly found in temperate to tropical seas, from reefs to the benthopelagic zone, but some species from the North Atlantic Ocean occur in into Arctic waters.
Bythitoidei is a suborder of the order Ophidiiformes, the cusk eels. They are distinguished from the other Ophidiform suborder, the Ophidioidei, by being largely viviparous.
Ophidiinae is a subfamily of the cusk eel family Ophidiidae. The species in the subfamily are characterised by having their pelvic fins situated far forward on the body and supported by an forward orientated extension of the pelvic girdle, they lack barbels on the mouth and chin and they are covered in small cycloid scales arranged in horizontal or diagonal rows. Some species have a modified swim bladder and the anterior vertebrae which enables them to generate sounds. and some of these modifications are sexually dimorphic and make the fish capable of generating sound. They have two rays in each ventral fin and the caudal fin has 9 rays. Most species are benthic and occur on the continental shelf.
Echiodon neotes is a fish species described by Markle and Olney, 1990. Echiodon neotes is part of the genus Echiodon and the subfamily Carapinae.
Onuxodon fowleri is a species of pearlfish first described by Smith, 1955. Onuxodon fowleri is part of the genus Onuxodon and the subfamily Carapinae. No subspecies are listed in the Catalog of Life.
