The effect of dextrose and probiotic Bacillus coagulans and Bacillus subtilis in Biomar’s commercial food on the growth factors and survival rate of Sward tail larvae (Xiphophorus helleri)

In order to study the effect of dextrose and mixed probiotic on growth factors and survival rate of Sward tail larvae, the larvae were fed three diets, including the first group (control diet) with commercial diet (Biomar, 0.4 mm at the rate of 5% of biomass), the second group with commercial diet (at the rate of 5% of biomass) and dextrose (0.4 g/k of commercial food weight) and the third group with mixture of commercial diet (at the rate of 5% of biomass), dextrose and two probiotics, including Bacillus coagulance and B. subtilis (0.4 g/k of commercial food weight). The larvae rearing continued for five weeks. The results showed that survival rate (SR%) and growth factors such as specific growth rate (SGR), body weight index (BWI), percent of the body weight index (PBWI%) and daily growth rate (GR%) and food conversion ratio (FCR) in the third treatment groups was better than others and a significant change were observed between the treatments (P≤0.05). Therefor feeding with probiotic diets, including B. coagulance and B. subtilis, improved the survival rate and growth factors and using it in the diet, is recommended.