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).
The pink brotula, Brosmodorsalis persicinus, is a species of viviparous brotula, the only member of the genus Brosmodorsalis. It is found along the northeast coast of the North Island of New Zealand from shallow depths to about 17 metres (56 ft). Their length is up to 6 centimetres (2.4 in).
The Fiordland brotula, Fiordichthys slartibartfasti, is a rare viviparous brotula found only in the Fiordland region of the South Island of New Zealand. It is inhabits spaces in rock rubble and is found at depths of from 10 to 12 metres. This species grows to a length of 11.1 centimetres (4.4 in) SL.
The Mexican blind brotula is a species of viviparous brotula endemic to Mexico, where it is found in sinkholes and caves. It is known as sak kay in Mayan and dama blanca ciega in Spanish. This cavefish grows to a standard length of 9.7 cm (3.8 in). It is the only known member of its genus.
Saccogaster is a genus of viviparous brotulas. They are found in the western Atlantic and Indo-Pacific.
Bidenichthys is a genus of viviparous brotulas.
The longtail cusk is a species of viviparous brotula native to the reefs around Australia. This species grows to a length of 5.8 centimetres (2.3 in) SL.
Brosmophyciops pautzkei, the slimy cuskeel or free-tailed reef brotula, is a species of viviparous brotulas found in tropical reefs of the Indian and Pacific Oceans. This species grows to 7 cm (2.8 in) total length. This species is the only known member of its genus. The specific name honours Clarence F. Pautzke, who was a former student of the describer of this species who went on to become the chief biologist in the Department of Game of Washington state and who was present on Bikini Atoll in 1946 and 1947 when the type specimen was collected.
The Red brotula is a species of viviparous brotula found along the North American Pacific coast from Alaska to Baja California. This fish is often displayed in public aquariums. This species grows to a length of 46 centimetres (18 in) TL. The red brotula is the only known member of its genus.
Microbrotula is a genus of viviparous brotulas.
Paradiancistrus is a genus of viviparous brotulas.
The Shaggy cusk is a species of viviparous brotula found in reefs around Rottnest Island, Western Australia. This species grows to a length of 13.6 centimetres (5.4 in) SL. This is the only known species in its genus. This species, while uncommon, is not considered to be at any risk.
The black brotula, also known as the black widow, is a species of viviparous brotula found in reefs of the western Atlantic Ocean where it occurs from the Bahamas in the north southwards to Brazil. This species grows to a length of 7.5 centimetres (3.0 in) TL. This species is the only known member of its genus.
Grammonus waikiki, or the Waikiki viviparous brotula, is a species of viviparous brotula found in the Hawaiian Islands where it occurs at depths of around 3–18 metres (9.8–59.1 ft).
Grammonus nagaredai, or the Nagareda's viviparous brotula, is a species of viviparous brotula found in the Hawaiian Islands where it occurs at depths of around 5 metres (16 ft) to 10 metres (33 ft).
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.
Paradiancistrus christmasensis, commonly known as the Christmas viviparous brotula, is a species of viviparous brotula native to the waters around Christmas Island and the south-eastern Indian Ocean. This species grows to a length of 6.8 centimetres (2.7 in) SL.
Cataetyx alleni, sometimes called Allen's brotula, is a species of fish in the family Bythitidae.
