Xenophallus umbratilis (Meek 1912)

Body thin, translucent and yellowish. Base of the first dorsal rays with a black blotch; in males the posterior edge of the dorsal fin is also black and sometimes the remainder of the fin is brilliant yellow. The males and young have 5 to 10 black bars on the side which are diffuse or absent in females. The gonopodium is asymmetrical and either dextral or sinistral; the apex of which in mature males bears a long upper projection and swelling below, both of which are membranous (Ref. 36880).

After 28 days gestation, about 15 to 50 young are born. Sexual maturity is reached after 3-4 months (Ref. 2060).

Inhabits waters of all velocities, between 35 and 590 m elevation, with temperatures of 21 to 37°C. Lives in small groups in brooks, creeks and along the shorelines of rivers where it feeds on detritus, filamentous algae, aquatic insects and ooze. Probably reproduces throughout the year (Ref. 36880).

Inhabits waters of all velocities, between 35 and 590 m elevation, with temperatures of 21 to 37°C. Lives in small groups in brooks, creeks and along the shorelines of rivers where it feeds on detritus, filamentous algae, aquatic insects and ooze. Probably reproduces throughout the year (Ref. 36880).

Xenophallus umbratilis is a species of poeciliid fish native to the countries of Nicaragua and Costa Rica. This species grows to a length of 4.5 centimetres (1.8 in) SL. It is the only known member of its genus.