The kotso (Paretroplus petiti) is a species of cichlid fish from northwestern Madagascar.

Currently rated as data deficient by the IUCN, this species is virtually unknown.

[1] The only known specimen is a juvenile that was collected more than 80 years ago.

[3] Erroneously, the name P. petiti has often been applied to members of a different species, P.

[3] The specific name honours the French zoologist and anatomist Georges Petit (1892-1973) of the Muséum national d’Histoire naturelle, who collected type.