Performance and carcass characteristics of Nile Tilapia (Oreochromis niloticus) reversed males of Thai and common strains at the starting and growing phases

The experiment was carried out to compare the performance of two Nile Tilapia strains (Thai and common) during the initial and growing phases. The fishes (50 in the starting phase and 40 in the growing phase) were assigned to a completely randomized design with two treatments and five replications. Better results were observed for the weight gain percentage, daily weight gain, feed:gain ratio and economic viability in both experimental phases, survival in the starting phase and final size in the growing phase for the Thai strain animals. In the growing phase, carcass (animal without the digest tract and branchial arcs) and filet yield showed no statistical differences among the treatments, however trunk yield (carcass without head, dorsal, ventral and pectoral skin and fins) were higher for the common strain animals. According to the morphometrical characteristics, higher relation between the head length/head height and standard length/total length for the Thai strain animals and a higher body width/trunk length relation for the common strain animals were observed. No difference was observed for the body height/trunk length relation for the studied strains. Thai strain animals showed better performance results in the initial and growing phases, however presented bigger head and smaller tail.