M Haghighi - Coldwater Fishes Research Center, Tonekabon, Iran
M Sharif Rohani - Iranian Fisheries Research Organization, Tehran, Iran

The aim of this study was to evaluate the effects of Aloe vera extract (AE) on the immunity responses and hematological parameters in rainbow trout (Oncorhynchus mykiss) fry to develop alternative drug to chemotherapeutics and antibiotics in aquaculture. 1200 rainbow trout (Oncorynchus mykiss) fry weighing 2±0.2 gram were randomly allocated into two treatment groups including: 1) placebo-treated group (control), 2) Aloe vera extract-treated group, each of three replicates. The fishes were hand-fed once a day with diet medicated AE or placebo at a rate of 1% of feed weight in the first feeding for 8 weeks. At the end of every two weeks 24 hrs after feeding, some of hematological and immunological parameters were analyzed. The results showed that serum total protein, albumin and globulin, respiratory burst activity, phagocytic activity and serum lysozyme activity vary among the two treatment groups which were found to be higher in AE-treated group (p<0.05). However there were no significant differences in hematological parameters between two groups. It was concluded that supplementation of AE at a rate of 1% registered higher immunological responses in compared to placebo group. Therefore, supplementation of AE in fish diets would enhance the nonspecific immunity responses and would be use particularly at time of outbreaks.

Herbal immunostimulant, Medicinal plants, Aloe vera, Fish