Monotypic fish genera

Episemion krystallinoron is a species of African rivuline native to Equatorial Guinea and Gabon.

Tridensimilis is a monotypic genus of freshwater ray-finned fishes belonging to the family Trichomycteridae, the pencil and parasitic catfishes, and the subfamily Tridentinae, the pygmy pencil catfishes. The only species in this genus is Tridensimilis venezuelae.

Sarmarutilus is a monospecific genus of freshwater ray-finned fish belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related fishes. The only species in this genus is Sarmarutilus rubilio, known as the rovella, South European roach or the Apennine roach, a species endemic to the Italian peninsula.

Parazacco is a monospecific genus of freshwater ray-finned fish belonging to the family Xenocyprididae, the East Asian minnows or sharpbellies. The only species in the genus is Parazacco spilurus, the predaceous chub, a fish found in China and Vietnam. The International Union for Conservation of Nature has classified this species as Data Deficient but Parazacco fasciatus, now regarded as a synonym of P. spilurus, is classified as being Least Concern.

Pelecus is a monospecific genus of freshwater and brackish water ray-finned fish belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related species. The only species in the genus is Pelecus cultratus, commonly known as the ziege, sichel, sabre carp or sabrefish, A fish found in Eastern Europe and adjacent Asian regions, inhabiting the lower reaches of rivers and brackish waters in the eastern Baltic Sea, Black Sea, Caspian Sea and Aral Sea basins. The ziege having no major threats, the IUCN lists it as being of Least Concern.

REDIRECT Small-eyed goby

Protanguilla palau is a species of eel, the only species in the genus Protanguilla (first eel), which is in turn the only genus in its family, Protanguillidae. Its common name is Palauan primitive cave eel. Individuals were found swimming in March 2010 in a deep underwater cave in a fringing reef off the coast of Palau.

The black ruff (Centrolophus niger) is a medusafish, the only member of the genus Centrolophus. It is a pelagic fish found in all tropical and temperate oceans at depths of . Its length is typically up to , but it may reach . Other common names include rudderfish and blackfish.

Lophiogobius ocellicauda is a species of freshwater Gobiidae, native to China and South Korea. This species is the only known member of its genus.

Micracanthicus vandragti is a species of suckermouth catfish endemic to Venezuela where it is found in the Ventuari River and adjacent Orinoco River. This species grows to a length of SL. It is the sole species of the genus Micracanthicus.

Bagropsis reinhardti is a species of long-whiskered catfish. This species reaches about in standard length and is endemic to Brazil where it is found in the Das Velhas River basin in São Francisco River drainage. It is considered a threatened species by Brazil's Ministry of the Environment.

Ephippion guttifer, commonly known as the prickly puffer, is a species of pufferfish native to the coasts of the eastern Atlantic Ocean from Gibraltar to Angola. This species grows to a length of TL. It is of importance to commercial fisheries and is popular as a gamefish. This species has the ability to get prickly when it puffs up. It is the only known member of the monotypic genus Ephippion.

Llanolebias stellifer is a species of killifish in the family Rivulidae. It is endemic to the Llanos, a part of the Orinoco basin in Venezuela, where it lives in shallow temporary waters (like ponds) in forests. This annual killifish grows to a total length of . It is the only known member of its genus, but it was formerly included in Rachovia.

Xenochromis hecqui is a species of cichlid endemic to Lake Tanganyika in East Africa. It is mainly found at depths of , but has been recorded somewhat deeper, even in waters virtually devoid of oxygen. This species is a scale eater, consuming the scales off of other fishes, but will also feed on copepods. It can reach a total length of up to . Currently it is the only known member of its genus.

Tricuspidalestes is monospecific genus of freshwater ray-finned fish belonging to the family Alestidae, the African tetras. The only species in the genus is Tricuspidalestes caeruleus, a species that is endemic to the Democratic Republic of Congo.

Denariusa australis, known commonly as the pennyfish, is a species of ray-finned fish in the family Ambassidae, the Asiatic glassfishes. It is the only member of the monotypic genus Denariusa. It is native to Papua New Guinea and Australia. This species grows to a length of SL.

Corynopoma is a monospecific genus of freshwater ray-finned fish belonging to the family Stevardiidae. The only species in the genus is Corynopoma riisei, the sword-tail characin, a species of characin found in Colombia, Trinidad and Tobago and Venezuela.

Grammatotria lemairii is a species of cichlid endemic to Lake Tanganyika in East Africa where it prefers areas with sandy substrates. This species can reach a length of TL. It is currently the only known member of its genus. The species is occasionally kept as an aquarium fish. The specific name honours Lieutenant Charles Lemaire (1863–1925) who was the leader of the Congo Free State Expedition, which collected specimens of fishes at Lake Tanganyika, including the type of G. lemairii.

Sagamia is a genus of fishes in the subfamily, Gobionellinae. Its only species is Sagamia geneionema. It is native to the coastal waters of Japan and Korea, where it lives near shore in areas with sandy substrates. The species grows to a length of SL.

REDIRECT Slow goby

Iotabrycon is a monospecific genus of freshwater ray-finned fish belonging to the family Stevardiidae. The only species in the genus is Iotabrycon praecox, a fish which is endemic to Ecuador, where it is found in the Vinces River basin..

Paraphago is a monospecific genus of freshwater ray-finned fish belonging to the family Distichodontidae. The only species in this genus is Paraphago rostratus . A species endemic to the Democratic Republic of Congo.

Pelagocephalus is a genus of pufferfish which is from the coasts of South Africa and New Zealand. It is monotypic, being represented by the single species, Pelagocephalus marki, also known as the rippled blaasop. This species grows to a length of about TL.

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Protonemacheilus longipectoralis is a species of hillstream loach that is endemic to China. It is the only species in its genus.

Lagodon is a monospecific genus of marine ray-finned fish belonging to the family Sparidae, which includes the seabreams and porgies. The only species in the genus is Lagodon rhomboides, the pinfish, red porgy, bream, pin perch, sand perch, butterfish or '''sailor's choice'''. This fish is found in the Western Atlantic Ocean and Gulf of Mexico.

Richardsonichthys, is a monotypic genus of marine ray-finned fish belonging to the subfamily Tetraroginae, the waspfishes, which is classified as part of the family Scorpaenidae, the scorpionfishes and their relatives. The only species in the genus is the whiteface waspfish (Richardsonichthys leucogaster), also known as the whitebelly roguefish, rouge fish, Torres Strait soldier fish or '''Richardson's waspfish'''. This species is native to reefs of the Indian Ocean and the western Pacific Ocean.

Pogoneleotris heterolepis is a species of fish in the family Butidae endemic to the marine and brackish waters of Malaysia. This species is the only known member of its genus.

Gnathocharax, is a monospecific genus of freshwater ray-finned fish belonging to the family Acestrorhynchidae, which includes the freshwater barracudas and the biting tetras. The only species in the genus is Gnathocharax steindachneri, also known as the arowana tetra. This fish is found in tropical freshwater habitats in the Orinoco and Amazon basins of South America.

Osteogeneiosus militaris, the soldier catfish, is a species of sea catfish found in the Indian and western Pacific Oceans from Pakistan to the Malay Archipelago. It is found in marine, brackish and fresh waters along the coasts. It grows to a length of 35 cm and is commercially caught for human consumption. It has a single pair stiff, sharp, maxillary barbels.

Polyplacapros is a monospecific genus of ray-finned fish belonging to the family Aracanidae, the temperate boxfishes or deep water boxfishes. The only species in the genus is Polyplacapros tyleri, '''Tyler's boxfish''', which is found in the southwestern Pacific Ocean.

Porogobius schlegelii is a species of goby native to brackish and fresh waters (occasionally entering marine waters) along the Atlantic coast of Africa from Senegal to the Democratic Republic of the Congo. It is also found in the islands of the Gulf of Guinea and Cape Verde. It occurs in inshore waters in lagoons, estuaries, the lower reaches of rivers and mangrove swamps. This species grows to a length of TL. This species is the only known member of its genus. The specific name honours the ichthyologist Hermann Schlegel (1804-1884) who supplied Günther with the type specimen from the Natural

Krefftichthys anderssoni is a species of lanternfish found circumglobally in the southern oceans. This species grows to a length of SL.

Pygopristis is a monospecific genus of freshwater ray-finned fishes belonging to the family Serrasalmidae, which includes the pacus, piranhas and related fishes.. The only species in the genus is Pygopristis denticulata, also known as the lobetoothed piranha,. This species is a rare South American characiform fish found in the Orinoco River basin, rivers of the northern and eastern Guiana Shield, and tributaries of the lower Amazon River. Like other piranhas, it is found in freshwater, with specimens of this species typically found in acidic clearwater or blackwater environments. Despite their

Tarumania is a genus of freshwater fish described in 2017. It contains a single species, Tarumania walkerae, and constitutes the only genus in the family Tarumaniidae. T. walkerae is a predatory species that hunts among the leaf litter on the bottom of flooded forests in the Rio Negro drainage basin.

REDIRECT Jack silverside

Neohomaloptera johorensis is a species of dwarf hillstream loach, it is the only member of its genus Neohomaloptera.

Micromoema xiphophora is a species of killifish from the family Rivulidae endemic to the Orinoco River basin in Venezuela where it is found in small pools in the forest. This annual killifish grows to a total length of . This species is the only known member of its genus.

Oligoobrycon is a monospecific genus of freshwater ray-finned fish belonging to the suborder Characoidei within the order Characiformes, the characins. The only species in the genus is Oligobrycon microstomus, a species of which is endemic to Brazil, where it is found in the upper middle Paraíba do Sul River basin. This taxon has not been assigned to a particular family within the Characoidei and is considered to be incertae sedis, i.e. its taxonomic affinities are, as yet, unclear. This fish has not been recorded since the holotype and paratype were collected in 1915.

Exallias brevis, the leopard blenny, (or Pāoo o kauila in Hawaiian) is a species of combtooth blenny found in coral reefs in the Pacific and Indian oceans. This species can be found in the aquarium trade and is the only known member of its genus.

Incara multisquamatus is a species of fish in the family Butidae known from brackish waters along the coasts of India and Australia. This species grows to a length of . This species is the only known member of its genus.

REDIRECT Topsmelt silverside

Aesopia cornuta is a species of sole native to the Indian and western Pacific Oceans. Its common names include the unicorn sole, thickray sole, banded sole, and dark thick-rayed sole. This species grows to a standard length of , and is the only known member of its genus.

Sparodon, commonly known as the white musselcracker, musselcracker seabream, mussel cracker seabream, brusher, or cracker. is a monotypic genus of fish in the family Sparidae. The type and only known species, Sparodon durbanensis, was first described and named by François Louis Nompar de Caumont de Laporte, comte de Castelnau, in 1861.

'''Cable's goby' (Eleotrica cableae'') is a species of goby endemic to reefs around the Galápagos Islands. This species grows to a length of SL. This species is the only known member of its genus. The specific name honours the United States Government biologist Louella E. Cable (1900–1986), who illustrated this goby for the describer Isaac Ginsburg, and drew his attention to its separated ventral fins.

Clupeocharax is a monospecific genus of freshwater ray-finned fish belonging to the family Alestidae, the African tetras. The only species in the genus is Clupeocharax schoutedeni a fish that is endemic to the Democratic Republic of Congo.

Albulichthys is a monospecific genus of freshwater ray-finned fish belonging to the family Cyprinidae, the family which includes the carps, barbs, minnows and related fishes. The only member of the genus is Albulichthys albuloides, although the population on the mainland and the population on the islands of the Malay Archipelago may be different species.