Leptopanchax is a genus of small fish, up to 5 cm (2.0 in) long, in the family Rivulidae.

[2] They are found in southeastern Brazil from Paraná to Rio de Janeiro.

[1][3] Depending on the exact species, they inhabit small seasonal channels in the Atlantic rainforest or temporary pools in open habitats.

[3] Several Leptopanchax species are very rare and L. sanguineus is possibly extinct.

[4] The species in Leptopanchax were formerly included in Leptolebias, but this makes the latter genus paraphyletic,[1] although they are still placed in that genus by Fishbase.