Monognathidae
by Jørgen G. Nielsen
Common names: none
Rather elongate eels with upper jaw absent. Frontals and possibly other elements of the rostral part of the skull fused and tapering into a strong fang with its tip protruding anteriorly in the roof of the mouth and with connected glands probably with poisonous function. Pectoral fins absent or reduced into skinflaps without rays. Dorsal and anal fins reaching tip of caudal.
Found pelagically from close to the bottom at 5400 meters to epipelagic layers, but most often below 2000 meters scattered in all oceans. Monognathids are rare fishes known from ca. 70 specimens. Oviparous; leptocephalus larva. Only one ripe male known. It is very different from the unripe males and females. The evident reduction of the jaws in mature specimens indicates that monognathids are one-time breeders.
Genera 1.
Recent revision: Bertelsen and Nielsen (1987).