Morphometry of white muscle fibers and performance of Nile tilapia (Oreochromis niloticus) fingerlings treated with methyltestosterone or a homeopathic complex.

Nile tilapia (Oreochromis niloticus), are widely used in fish farming, hormonal treatments are used to increase productivity. Studies of the characteristics of the fiber types are important in species that have well developed muscle mass, such as Nile tilapia. A total of 4800 post-larval fish were randomly assigned by tank to receive one of three treatments: Control (30°GL alcohol), Homeopathic complex (Homeopatila RS) or Hormone (17-α-methyltestosterone) supplemented in the feed for 28 days. Survival and morphological parameters were measured at day 45. At day 45, the survival rates were 54.1% (Control), 87.8% (Homeopathy), 50.3% (Hormone). The mean final weight for Homeopathy was statistically significantly lower (1.07 g) than the other two groups: Control (1.81 g) and Hormone (2.04 g). Mean total lengths were Control (4.75 cm), Hormone (4.49 cm), statistically significantly different from Homeopathy (3.83 cm). Average partial length, trunk length, height and body width were significantly lower for Homeopathy than Control or Hormone (p<0.05) Homeopathy treated fish had significantly greater muscle fiber diameter than the other two groups. Fish treated with the homeopathic complex had improved survival and muscle fiber hypertrophy, but were smaller (probably related to increased survival and overcrowding) compared to fingerlings treated with synthetic hormone or control.