Effect of temperature and feed rate on the body shape of Oreochromis shiranus, a widely-cultured tilapia species in Malawi

Document Type : Original Article


Lilongwe University of Agriculture and Natural Resources, Bunda College, Aquaculture and Fisheries Science Department, P.O. Box 219, Lilongwe, Malawi


Considering the vitalness of traits such as body shape and size in influencing the marketability of fish, geometric morphometrics was utilized to explore if raising fish at different temperatures and feedrates would affect such important traits. MANOVA revealed significant differences in body shape among fish raised at different temperatures but not those fed at different levels of their body weight. In general, the fish that were raised at 20°C, regardless of the feedrate, had shorter but deeper bodies, larger eyes and longer heads as opposed to the longer and slender bodies, smaller eyes and shorter heads found in those reared at 25°C and 30°C. On size, ANOVA revealed significant differences along temperature and feedrate gradients in a way that fish reared at 20°C were the smallest, followed by those at 25°C and then the largest were those at 30°C. On feedrate, it was only at 30°C where fish fed at 6% body weight were significantly larger in size than those fed at 3% body weight. These findings are discussed in terms of best management practices, especially on how to combine such two abiotic factors in order to maximize growth within the shortest period possible, considering the economical implications.