Changes of fast muscle cellularity in male and female Nile tilapia (Oreochromis niloticus) over three generations of domestication

The demand for food consumption is increasing as the population of the world is growing. Aquaculture industries are playing a crucial role to maximize the production and quality of fish. Domestication has been extensively used in animals to modify phenotypes such as growth. Nile tilapia (O. niloticus) is one of the most consumed fish globally. The study aimed to examine the skeletal muscle cellularity in three generations (F1, F2, and F3) of Nile tilapia under domestication. The F0 offspring were bred in captivity and the F1 generation was obtained successfully. After three months of F1 generation in captivity, selected and control groups (including male and female) were divided on the basis of their weight. Selected fish had a weight at least 10 % higher than the average weight of all fish. The other generations F2 and F3 also followed the same procedure to divide into selected and control groups. Selected and control groups were kept in separate tanks. Fast muscle was sampled from fish across all three captivity generations (F1, F2 and F3), albeit at different ages. In each generation, we picked randomly 40 fish (20 males and 20 females) from each selected and control group. Biometric data such as body weight, total length and standard length were recorded for each fish. In addition, histological samples were prepared to examine the growth and development of fast muscle at each generation. In each generation, all male groups had larger fast muscle fibre diameter, weight and length than female groups. The study shows that the selected male groups from each generation contained the highest mean values for weight and length than control male groups. There were significant differences (P