Cyclothone Goode and Bean, 1882
Small fishes, fairly elongate; mouth large; pseudobranch absent; gill filaments longer in males; branchiostegal rays 13-14 (5-6 on epihyal). Dorsal and anal fin origins about opposite; last dorsal and anal finrays not split to base; adipose dorsal fin absent; anus nearer to pelvic fin base than to anal fin origin or at midway. Swimbladder regressed in adults. Scales present or absent.
Photophores: absent on isthmus; SO absent; OA present, ending at or about anal fin origin; AC less than 25; OP 2; 1-2 VAV anterior to anus (one species, C. obscura, without photophores).
Oceanic, or pseudoceanic, temperate-tropical, meso- or bathypelagic, showing size depth relationship, the largest fishes deepest; postlarvae near surface, migrating to adult depths at metamorphosis; no diel vertical migrations. Very common. Feeding mainly on small crustaceans. Most dioecious, but some protandrous hermaphrodites; males macrosmatic, females microsmatic; development of post-larval photophores simultaneous for the majority of ventral serial photophores.
Species 11 (in addition, I undescribed from the Pacific, presented by Kobayashi (1973) but as yet unpublished); in Clofnam area 9.
Recent revisions: Mukhacheva (1972, 1980); Kobayashi (1973); Quero (1974); Badcock (1982).
Species of this genus in the program:
Cyclothone acclinidens
Cyclothone alba
Cyclothone braueri
Cyclothone livida
Cyclothone microdon
Cyclothone obscura
Cyclothone pallida
Cyclothone pseudopallida
Cyclothone pygmaea