The name Aphyosemion can be divided into two parts. Aphye is derived from Greek and means “little fish”. Semeion means “with flag” or “pennant”. This is a reference to the elongated fin rays of the dorsal and anal fin. The name Mengila is a reference to the driver and guide François Mengila from Gabon.
The males of the Aphyosemion mengilai have a bluish ground colour with red spots. The dorsal and anal fins are blue which is edged with a black band. This black band also distinguishes it from the other species that look a lot like this Aphosemion. Aphyosemion grelli most closely resembles this species; however, Aphyosemion mengilai has more fin rays in the anal and dorsal fin. Another distinction is length. Aphyosemion mengilai can reach a total length of about 5 centimetres whereas Aphyosemion grelli does not grow longer than about 4 centimetres.
Aphyosemion mengilai comes from a small area in Gabon. They inhabit the basin of the Ikoy River which flows through the Chaillu Massif in Gabon. They inhabit the small shallow streams with a muddy bottom and mostly leaves on the ground.
John de Lange