The length-weight relationship and condition factor of Hemichromis fasciatus and Tilapia melanopleura in Kontagora Reservoir were studied. Two thousand eight hundred and seventy-two specimens were collected between January and December 2007 using a fleet of graded experimental gill nets and analysed. The parameters a and b of the length-weight relationship and condition factor K are presented for the fish species. The value of b varied between 3.093 and 3.312, with the mean b = 3.203 ± 2.07 at p< 0.05 and the K-values significantly (p< 0.05) ranged between 2.76 and 4.14. This indicates that the two species had positive correlation and positive allometric growth, with the rate of increase in body length being proportional to the rate of increase in body weight. The condition of the lake is favourable for the survival and growth of the fish species.