[2] This fish was first described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae.

Females are larger and much heavier than males, reaching an average of 18.5 cm (7.3 in) standard length (SL) and 80 g (2.8 oz) in weight, while males reach an average of 14.5 cm (5.7 in) SL and 31 g (1.1 oz) in weight.

[10] Female fish also have a modified scale called a foriculum covering either the left or right genital opening.

[4] A. anableps can be distinguished from other species in the genus by the small number and large size of its scales.

Unlike A. microlepis, however, A. anableps can survive in freshwater environments for extended periods.

A large part of its diet consists of detritus, but the highest diversity of prey items comes from insects.

[16] It has occasionally been observed catching insects by jumping in the air,[14] but otherwise, it ingests prey on or near the surface.

was the main food item, supplemented by insects and shore crabs (family Grapsidae).

[13] A. anableps is affected by the parasitic praniza larvae of isopods in the family Gnathiidae, which feed on its blood by attaching to the gills and skin.

The eyes are divided in half laterally by a band of tissue, which is kept at the water level.

Cartilage fills in empty space in the top of the skull between the eyes, which later hardens into bone.

[9][12] Females may carry between 1–37 eggs, which stay and develop as embryos in the ovarian follicles until the yolk sac is absorbed and the fish are born.

The ovaries and follicles change dramatically in both size and structure to accommodate the embryos as they grow, but return to normal after birth.

[10][9][12][21] In males, the rays of the anal fin develop into a long bony structure called a gonopodium, which is used to deposit sperm.

The rays of the anal fin curve to form an asymmetrical cylindrical structure that almost fully encloses a sperm duct (distinguishing it from the gonopodia in families Goodeidae and Poeciliidae).

During the development of the gonopodium, an additional anteriormost anal fin ray forms that is not present in females or juveniles.

[22] The asymmetry in females comes from the foriculum, which is a modified scale that covers the oviduct, located behind the vent.

The foriculum only opens to one side, meaning that right-handed males can only mate with left-handed females, and vice versa.

Breeding experiments with this species may suggest that the handedness of the gonopodium is determined randomly, and is not heritable or dependent on environmental conditions.