Chlorella vulgaris is focused for its potential as immunostimulants against the infectious diseases of fish. The present study was planned to demonstrate the immunostimulant effect of Chlorella vulgaris and evaluate its effects on the resistance of Nile tilapia (Oreochromis niloticus) challenged with Aeromonas sobria. One hundred and twenty of Nile Tilapia were divided into four groups supplemented with diet incorporated with Chlorella vulgaris at levels of zero, 0.5, 1 and 1.5 gm/kg standard diet for 60 days. After the experimental period, results indicated that fish supplemented with Chlorella vulgaris produced significant increase in total white blood cell (WBC), lymphocyte & granulocyte counts, Phagocytic index with significant increase in serum lysozyme activity, total serum protein, albumin level, and globulin levels. In addition, Chlorella vulgaris produced 100% & 83% of protection in Nile tilapia infected with Aeromonas sobria when supplemented at levels of 1 & 1.5 gm/kg, respectively.
This study concluded that Chlorella vulgaris can be used as an immunostimulants in fish.