Although many studies have been done on the various effects of garlic on fish, the impact of garlic on steroid hormones has not been studied so far. In the present study, the effect of aqueous garlic extract on sex steroid hormones, fry production, digestive enzyme activities, growth performance and survival of Poecilia reticulata were evaluated. A total of 360 P. reticulata fries (0.013±0.001 g) were randomly stocked in 12 experimental glass tanks (50 l) at the density of 30 fish per tank. The fries were fed diets supplemented with aqueous garlic extract at 0 (Control), 1.00 (G1), 1.50 (G2) and 2.00 (G3) ml kg-1 diet three times a day at a ratio of 2.5% of their body weight for a period of 120 days. The experiment was carried out through a completely randomized design (triplicated). Results demonstrated that the inclusion of garlic extract in the diet did not have any significant effect on growth performance and fry production. The survival of G2 treatment was significantly higher with respect to the control, G1 and G3 (P<0.05). The concentrations of sex steroid hormones (estradiol, testosterone, 17α-hydroxyprogesterone and progesterone) and the activity of digestive enzymes (protease, lipase, and amylase) were significantly higher in G2, with respect to the control and the other treatments (P<0.05). Based on the polynomial regression models, the recommended dietary concentration of garlic extract for P. reticulata should be 1.64±0.03 and 1.63±1.01 ml kg-1 to obtain higher activities of digestive enzymes and sex steroids respectively.

Keywords