This genus was erected by Costa in 1995 and since then seen as distinct genus. It was originally designated to the also monotypic species Plesiolebias damascenoi (Costa 1991).

The genus Stenolebias is belonging to the family group of Plesiolebiatini. It differs from most other members of the group by its slender body shape. The name "Steno" (Stenos =narrow in Greek) and "lebias" which refers to another Cyprinodontiform genus.

The genus contains only 2 members up to now.

Both species within the genus are known only from a small area situated within the Rio Paraguay basin of central western Brasil.

For me it was not possible jet to obtain one of both species for behavior study and/or photograph both males and females. They are seldom available to aquarists or scientist.

Behaviour:

This species group prefers to live in larger bodies of stagnant water that can be of temporary nature like swamps, flooded land and pools. They can be found in savannah- and forest like areas, mostly on a muddy bottom.

General behavior is like that from most Simpsonichthys species as they like to dwell in small groups and are not very active in there environment. Not fast swimming but more peaceful standing in shaded places. They eat, as most other annuals do, mosquito larvae and small flying insects or crustacean.