The acquisition or loss of Clinostomum tilapiae parasites by Oreochromis niloticus was studied. Four groups of 25 healthy fishes were stocked in the upper part of serial experimental ponds, while another four groups of 25 infected fishes were also stocked at the rear part of the serial experimental ponds. All the groups were fed at 3% body weight with the same compounded fish feed. Acquisition or loss of parasites and growth was monitored for a period of six months. The mean relative growth rate was 11.04kg/month for the healthy fishes and 5.62g/month for the infected fishes. The mean specific growth rate was 38.75% and 31.25% for the healthy and infected groups respectively. However the results were not statistically significant (p > 0.05). The parasite did not multiply on the host body rather the infection rate reduced from 100% to between 44 and 78%, parasite burden was reduced from an average of 3 per fish to 2.25 while the healthy fish acquired the parasite and the average burden was 2.15. The mean values of the prevailing water quality parameters were within the optimum range acceptable in fish culture systems in the tropics
