Populations of the Tilapia known as T. meeki Pollogrin 1911, and T. mariae Boulengor, 1899, have been studied in the region of the Niger delta. T. mariae was originally described from small fishes with a pattern of vertical bars on the body, T. meeki from adults with a series of blotches along the middle of the side. These are here shown to belong to a single species, which undergoes a colour-pattern change at 140 to 180 mm. and must take the older name, T. mariae. T. mariae is a Substrate-spawner. The brreding pair show no differences in colour and both parents share in fanning the eggs and guarding the brood.