Petrocephalus catostoma (Günther, 1866) has four different subspecies; Petrocephalus catostoma catostoma, P. c. congicus, P. c. haullevillei, and P. c. tanensis. This study was set out to find out if there are morphological and meristic variability among specimens of Petrocephalus. We examined 132 specimens from Burundi, Tanzania, Zambia, Botswana, Gabon, Angola and Malawi. The collections were from the Musée royal de l Afrique Centrale, Tervuren (MRAC) and type specimens 39 from the British Museum of Natural History (BMNH). Methods for taking counts and measurements followed those of Boden et al. 1997. Covariance of matrix for measurements resulted in a single group which was impossible to divide logically into subgroups. However, correlation matrix for counts, resulted in two subgroups, with P. c. haulleville completely differentiating from the other subspecies. The P. c. haullevillei group had fewer scales from the origin of dorsal and anal fin, 8-9 SDLL, 9-11 SALL, compared to 9-17 SDLL and 9-18 SALL in the other group. The number of lower teeth was 14-20 compare to 14-24 in the other group. P. c. haulleville is probably a different species and should be classified as such.