By Koichi Shibukawa

Discotrema lineata

Small-sized marine fishes (few in freshwater). Body moderately elongate, more or less depressed anteriorly, subcylindrical or compressed posteriorly; head and body naked; dorsal and anal fins restricted to posterior half of body; pelvic fins modified into a ventral sucking disc. Single dorsal fin, with 3-21 soft rays; pectoral fin with 16-31 soft rays (exclusive of Australian genus Alabes with no dorsal, anal, pectoral and pelvic fin rays). Color: highly variable; sometimes with blotches, lines, bands, spots, or other patterns.

Similar families occurring in the area. Blenniidae: no ventral sucking disc; origin of dorsal fin at anterior part of body. Gobiidae: usually two dorsal fins; slender and flexible (rarely pungent and non-flexible) spines on dorsal and anal fins.

Remarks. Typically found in shallow coastal waters such as coral and rocky reefs and boulders, whereas few found in freshwater areas. Some colorful species often treated as aquarium fish.