Rivulus gili is described from the Rio Preto drainage, Rio Negro basin, Amazonas state, Brazil. The new species was found in a small creek called Garukana, within a tropical rainforest in the vicinity of Campinas do Rio Preto. This miniature species is considered to be a member of the subgenus Owiyeye, which is diagnosed by a unique frontal squamation. Laimosemion gili can be distinguished from all other species of the genus by the unique colour pattern, having a metallic blue stripe starting midbody which reaches the origin of the caudal fin. The new species is apparently related to L. romeri, sharing with this latter species a broad black stripe on flanks in males, but is easily distinguished by some other morphological characters.

This species breeding is not documented yet but will not differ much from what is normal for other miniature Rivulus (Laimosemion).

Remarks :

Max. size (23.2 mm).
Dorsal 5 - 6,
Anal 8 - 9,
D/A 0.0,
LL scale count (average) 29
Pre- dorsal length to % SL – 73.1 %
Depth to % SL – 12 %