Effects of different levels of thyme, Zataria multiflora on growth performance, body chemical composition and resistance to environmental stressors in Zebra fish, Danio rerio

The aim of the present study was to evaluate effects of different levels of thyme, Zataria multiflora (n growth performance, body chemical composition and resistance to environmental stressors such as temperature and acidity in zebra fish, Danio rerio. 480 Fish with an average weight of 0.33 ± 0.08 g were distributed in 12 tanks and fed by four isonitrogenous and isoenergetic diets including replacement levels of 0, 1, 1.5 and 2% thyme powder (T0, T1%, T1.5% and T2% respectively). After 10 weeks, growth performance, survival and body proximate composition, were determined, then 10 fish per tank were taken for environmental resistance and 10 fish per tank for the body composition analysis. According to the results, the highest final weight, weight gain, body weight increase, specific growth rate and protein efficiency ratio were obtained in T2% (p < 0.05), while the lowest feed conversion ratio in T2%. It was also true for the highest survival rates which were also found in T2% but not significant (p>0.05). Differences among treatments in survival rate against acidity and temperatures were also not significant (p>0.05). Significant difference between treatments were observed in body composition including moisture, protein, fat and ash (p<0.05). In conclusion, using thyme powder at the food dietary of the zebra fish, can affect the growth performance, carcass composition and survival rate of D. rerio but not on resistance against the environmental stressors.