Rheocles has a restricted distribution, being found only in certain forested freshwater habitats in the central and eastern highlands of Madagascar including the Nosivolo River.

[1] The genus appears to feed almost exclusively on allochthonous material, primarily insects falling onto the water surface.

[2] However, in a 2004 analysis, it was found that Rheocles was paraphyletic, forming two distinct clades.

[2] R. vatosa and R. derhami are sexually dimorphic, with males exhibiting larger adult size, enhanced coloration and pigmentation, as well as pronounced development of the unpaired fins.

[3] Its close association with forested biotopes suggests that, like so many other rainforest-adapted series, Rheocles is extremely vulnerable to deforestation pressure.