Pachypanchax arnoulti is a species of aplocheilid killifish[2] endemic to Madagascar.

Its natural habitat is rivers and lakes.

It is threatened by habitat loss and invasive species.

[3][1] The specific name of this fish honours the French ichthyologist and herpetologist Jacques Arnoult (1914-1995) in recognition of his contributions to the knowledge of Madagascar's fish fauna.

[4] It was described by Paul V. Loiselle in 2006 with the type locality given as "Swamp draining into tributary stream of Ikopa River, flowing parallel to RN-4 at Antanimbray village, 17°10'79"S, 46°50'97"E, Betsiboka River drainage, Madagascar, elevation 246 meters".