Response of African Catfish Hybrid to Diets Supplemented with Varying Levels of Tryptophan

Background and Objective: The hybrids of the African catfish are commonly cultured in Africa, but cannibalism exhibited by the fish generally limits their production. Many efforts to address the situation have had limited success. Tryptophan has been added to the feeds of certain fish to mitigate cannibalism with some success. This work assessed the possibility of controlling cannibalism in cultured Heterobranchus longifilis×Clarias gariepinus with dietary tryptophan. Materials and Methods: Six diets were prepared to contain in each a particular concentration of tryptophan from 0.0-2.5%, differing by 0.5% from the next feed. The hybrid fingerlings were placed 45 L in a 45 L round plastic tank containing 40 L of water, maintained by 100% flow-through water exchange per day. Feeding was 4% of body weight daily. A complete randomized design with 6 feed treatments and 3 replicates was employed. Weight and survival data were taken and the results analyzed with ANOVA (p = 0.5). Results: There were significantly higher survival rates and lowest cannibalism at 0.5, 1.0 and 1.50%, which was more as a result of the percentage composition of cannibals, which were significantly different in some treatments, than the effect of tryptophan. No effects were seen in the coefficient of variation in weight, heterogeneity, and growth performance. Conclusion: The study revealed that the diets of African catfish hybrids could be supplemented with up to 1.5% tryptophan, in conjunction with other measures, to control cannibalism. It was not possible to evaluate the effect of tryptophan on other growing stages of the fish, try many other concentrations, or exceed the experimental duration. Further research should address these limitations to provide more comprehensive information to the culturists of this species.