In the research project performed, the effects of different levels of hydro-alcoholic extract Vitex agnus-castus were investigated as nutritional supplement on growth parameters of Danio rerio for 4 months. Since the beginning of the feeding phase up to the age of 4 months (average weight: 2.1±0.1g, length: 5.2±0.3 cm), larvae were fed with expe-rimental diets. Fish treated with diets containing plant extracts had higher growth and survival rate than the control gr-oup (p<0.05). Differences in the level of the extract had no significant effect on the survival rate (p<0.05). The results revealed that the diet containing 15 gr of the extract resulted in the best FCR significantly (p<0.05). By increasing the extract in the diet during the experiment, SGR increased. The highest and the lowest %BWG were observed in treatm-ents T3 and T0 respectively (p<0.05). The highest CF was observed in T3 and the lowest was obtained in T0. All in all, this study proposed that the addition of 15 gr of hydro-alcoholic extract of Vitex agnus-castus in the diet of zebrafish could improve the performance of the growth indices and increase the final biomass. In addition, this extract could be considered as a suitable supplement for Cyprinidae diet.