Effects of Tribullus terrestris extract on masculinization, growth indices, sex deteminationreversal and steroid hormones level in Zebra fish (Danio rerio)

Tribulus terrestris is a plant that has been introduced in aquaculture as a inducer for masculinization and stimulating growth in fish. This study has investigated the effect of the different levels of T. terrestris extract (TE) on growth indices, sex ratio and steroid hormones of Zebra fish (Danio rerio) that fed with four concentrations of 0 (T0), 50 (T1), 100 (T2) and 200 (T3) mg TE/kg of food during 60 days. 180 Zebra fish larvae (0.01±0.003 g average weight) were distributed into 12 aquaria (15 fish/aquarium) in four treatment groups and three replicates per each group. The results indicated fishes receiving higher dose of TE were in better conditions rather than the control group in terms of the growth rate (p<0.05). The highest male to female ratio has been achieved in fish fed with T2 diet (70.83±3.818). The values of testosterone and dehydroepiandrosterone were considerably different in the treatment groups compared with the control group and the maximum amount of these hormones were measured in fish fed with T3 and T2 diets, respectively (p<0.05). According to the histology results, the gonads have been completely formed and the growth of body performance and masculinization percentage showed a significant increase in fish fed with T2 diet compared with the other treatment groups.