Leptocephalus is a genus that was used for species of larval eels, called leptocephali, that were thought to be new fish species, or whose adult eel species were not known. Leptocephali differ so much in appearance from their adults that the larvae and adults of eels are not easily matched, and when first discovered, leptocephali were thought to be a distinct type of fishes, but not eels. Because of this, the genus designation of Leptocephalus was used for a while for unidentified leptocephali even after it was known that these were the larvae of eels thus becoming a "wastebasket taxon", but this practice is no longer used. Examples of marine congrid larvae, found in the western Indian Ocean and the Red Sea that were named this way are listed below. Only two species in two families are currently treated as having any validity, though the validity of L. bellottii is strongly in doubt.
Bathycongrus is a genus of eels in the family Congridae.
Ariosoma meeki is an eel in the family Congridae. It was described by David Starr Jordan and John Otterbein Snyder in 1900, originally under the genus Congrellus. It is a subtropical, marine eel which is known from Japan and the Peng-hu Islands, in the northwestern Pacific Ocean. Males are known to reach a maximum total length of 53 centimetres.
Bathycongrus bleekeri is an eel in the family Congridae. It was described by Henry Weed Fowler in 1934. It is a tropical, marine eel which is known from the Philippines, in the western central Pacific Ocean. It is known to dwell at a depth of 51 metres. Males can reach a maximum total length of 8 centimetres.
The Bullish conger is an eel in the family Congridae. It was described by David G. Smith and Robert H. Kanazawa in 1977, originally under the genus Rhechias. It is a marine, deep water-dwelling eel which is known from the Gulf of Mexico to the Amazon, in the western Atlantic Ocean. It dwells at a depth range of 366–475 meters. Males can reach a maximum total length of 39.5 centimeters.
The dubious conger is an eel in the family Congridae. It was described by Charles Marcus Breder Jr. in 1927, originally under the genus Pseudoxenomystax. It is a marine, deep water-dwelling eel which is known from the western Atlantic Ocean, including the United States, the Gulf of Mexico, Caribbean Sea, and the Guianas. It dwells at a depth range of 128–886 meters. Males can reach a maximum total length of 44.3 centimetres (1.45 ft) centimeters.
The lined conger is an eel in the family Congridae. It was described by Albert Günther in 1887, originally under the genus Congromuraena. It is a marine, deep water-dwelling eel which is known from the western Indian Ocean to the southwestern Pacific Ocean, including Indonesia and Hawaii. It dwells at a depth range of 270–1270 metres.
The shorthead conger is an eel in the family Congridae. It was described by Charles Henry Gilbert in 1891, originally under the genus Ophisoma. It is a marine, deep water-dwelling eel which is known from the Gulf of California to Panama, in the eastern central Pacific Ocean. It dwells at a depth range of 265–590 metres. Males can reach a maximum total length of 25 centimetres.
The Toothy conger is an eel in the family Congridae. It was described by Henry Weed Fowler in 1934, originally under the genus Uranoconger. It is a marine, deep water-dwelling eel which is known from the western Indian and southwestern Pacific Ocean, including the Philippines and Indonesia. It is known to dwell at a depth of 886 metres. Males can reach a maximum total length of 4.3 centimetres.
Bathycongrus polyporus is an eel in the family Congridae. It was described by David G. Smith and Robert H. Kanazawa in 1977, originally under the genus Rhechias. It is a marine, deep water-dwelling eel which is known from the Straits of Florida and the northern coast of Cuba, in the western central Atlantic Ocean. It dwells at a depth range of 439–549 meters. Males can reach a maximum total length of 43 centimeters.
Bathycongrus trilineatus is an eel in the family Congridae. It was described by Peter Henry John Castle in 1964, originally under the genus Leptocephalus. It is a tropical, marine eel which is known from the western central Pacific Ocean. It is known to dwell at a depth of 50 metres.
The largehead conger is an eel in the family Congridae. It was described by Samuel Garman in 1899, originally under the genus Uroconger. It is a marine, deep water-dwelling eel which is known from southern Canada to Chile, in the eastern Pacific Ocean. It dwells at a depth range of 165–935 metres. Males can reach a maximum total length of 100 centimetres.
The neighbor conger is an eel in the family Congridae. It was described by Samuel Garman in 1899, originally under the genus Uroconger. It is a marine, deep water-dwelling eel that is known from the southwestern and western central Atlantic Ocean, including the Bahamas, Brazil, Cuba, and Mexico. It dwells at a depth range of 101–503 metres (331–1,650 ft). Males can reach a maximum total length of 46.2 centimetres (18.2 in).
The Longnose conger is an eel in the family Congridae. It was described by Peter Henry John Castle in 1968, originally under the genus Congrina. It is a marine, deep water-dwelling eel which is known from the Indo-Western Pacific, including Mozambique, Natal, South Africa, Japan, the Philippines, and Indonesia. It dwells at a depth range of 250–500 metres. Males can reach a maximum total length of 55 centimetres.
Conger erebennus is an eel in the family Congridae. It was described by David Starr Jordan and John Otterbein Snyder in 1901, originally under the genus Leptocephalus. It is a marine, temperate water-dwelling eel which is known from Japan and the Korean Peninsula, in the northwestern Pacific Ocean. It is also called the "anaconda" アナコンダ in Tokyo, Japan.
Gnathophis nystromi is an eel in the family Congridae. It was described by David Starr Jordan and John Otterbein Snyder in 1901, originally under the genus Leptocephalus. It contains two subspecies, Gnathophis nystromi nystromi, and Gnathophis nystromi ginanago, which was described by Hirotoshi Asano in 1958, originally under the genus Rhynchocymba.
Rhynchoconger ectenurus, known commonly as the longnose conger in Australia, is an eel in the family Congridae. It was described by David Starr Jordan in Robert Earl Richardson in 1909, originally under the genus Leptocephalus. It is a marine, subtropical eel which is known from the western Pacific Ocean, including northern Australia, Japan, the Korean Peninsula, and the eastern China Sea. It inhabits soft sediments on the continental shelf and slope. Males can reach a maximum total length of 65 centimetres.
Cynoponticus coniceps, the red pike conger or conehead eel, is an eel in the family Muraenesocidae. It was described by David Starr Jordan and Charles Henry Gilbert in 1882, originally under the genus Muraenesox. It is a marine, tropical eel which is known from the eastern central and southeastern Pacific Ocean, including Mexico, Ecuador, Colombia, Costa Rica, Guatemala, El Salvador, Honduras, Panama, Peru, and Nicaragua. It dwells at a depth range of 10 to 100 metres, and inhabits sediments of sand and mud. Males can reach a maximum total length of 202 centimetres (80 in); the maximum recorded weight is 11.0 kilograms (24.3 lb).
The blacktail buckbill eel, also known commonly as the blacktail duckbill, or the duckbill eel in Malaysia, is an eel in the family Nettastomatidae. It was described by David Starr Jordan and John Otterbein Snyder in 1901, originally under the genus Chlopsis. It is a marine, tropical eel which is known from the western Pacific Ocean, including Japan, China, Malaysia, the Philippines, and Taiwan. It is known to dwell at a depth range of 100 to 500 meters. Males can reach a maximum total length of 50 centimeters (20 in).
Scolecenchelys aoki, the Misaki worm eel or Japan earthworm conger, is an eel in the family Ophichthidae. It was described by David Starr Jordan and John Otterbein Snyder in 1901, originally under the genus Muraenichthys. It is a marine, temperate water-dwelling eel which is known from reefs in Japan, in the northwestern Pacific Ocean. Males can reach a maximum total length of 44.8 centimetres (17.6 in).
