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.

Zebra fish is an important species in genetics and considering the proximity of its genome to the human genome, investigating the expression of some of the growth and appetite genes during its larvae development is essential. Genes coding growth and appetite (GH and ghrelin) hormones are involved in the synthesis and release of growth hormone, which can be considered to be economic genes in pisciculture. Given the importance of these genes during the early larvae development stages, this study was performed to assess their activity. Samples were collected at 4, 7, 10, 15, 30 and 45 post-hatching days. Samples were immediately placed in liquid nitrogen (-196 degree centigrade) and then stored in a freezer at -80 degree centigrade until RNA extraction (using RNX-Plus kit). To analyze normal expression of target genes, reference gene β-actin was used by 2^-∆∆Ct method. The expression of genes associated with the growth and appetite was significantly different at various stages of the development of zebra fish, as the gene expression of GH on day 4 and ghrelin gene on day 10 after hatching were significantly higher compared with other samples (P<0.05). Overall, the expression of GH and ghrelin genes at the early stages of growth is higher than other fish developmental stages due to their great importance in the survival of larvae at these stages of life.
 
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