The genus Leptopanchax was erected by Costa in 2016 to fascilitate a new genus for 4 species formerly placed in the genus Leptolebias.

Leptopanchax is distinguished from Leptolebias by having Caudal fin symmetrical (vs. asymmetrical) in male, anterior proximal radials of Anal fin not placed in close proximity in male (vs. placed in close proximity), urogenital papilla not in close proximity to Anal fin origin in male (vs. in close proximity), basal portion of urogenital papilla not forming pronounced wide structure in male (vs. forming distinctively wide structure), absence of thickened tissue on basal portion of Anal fin in male (vs. presence), absence of canary yellow stripes on sides of male (vs. presence), absence of broad white stripe ventrally bordered by narrow black stripe on lower margin of Caudal fin in males (vs. presence), absence of dark reddish chocolate brown stripe between Pectoral fin base and posterior portion of Anal fin base in male (vs. presence), absence of small round dark reddish brown spots on Dorsal fin in male (vs. presence)