Neoheterandria elegans

Background

Neoheterandria elegans is found in the Truando River in Colombia. The front half of the fish is mostly silver, while the rear half displays alternating gold and black vertical bars. Males grow to 2.0 centimetres (0.79 in) and females to 2.5 centimetres (0.98 in).

Like most poeciliids, it is a livebearer. The male uses a modified anal fin, or gonopodium, to deliver sperm to the female. The gonopodium of Neoheterandria elegans males has a long, bony rod that projects forward and downward, which distinguishes them from the genus Xenophallus, whose males have gonopodia that project either to the right or to the left. Unlike some male livebearers that court females, male Neoheterandria elegans copulate by thrusting their gonopodium at the female's vent.

Females do not drop their whole brood at once like guppies or swordtails; instead, they generally release between 2 and 4 fry each day for several days.