This study was carried out to evaluate the comparative effects of some immunostimulants and antibiotic supplementation on growth performance parameters, survival rate, diseases resistance (Aeromonas hydrophila)and  immune status of Nile tilapia frys. A total number of 500 Oreochromis niloticus fry, with an average initial weight (0.35 ±0.05 g) were stocked at 5 treatments with 2 replicate, control group(Gr1) and from Gr2:Gr5 provided with dietary supplementation as following: Garlic 40 g/kg purpurea extract 4gm/kg, yeast 4 g/kg and ciprofloxacine  1gm/kg of the diet, for a three month period.The results revealed that groups treated with Echinacea, Garlic and yeast, significally improved the growth performance parameters, but Echinacea purpurea gave the best feed conversion ratio. In addition, increasing the relative protection levels against Aeromonas hydrophila which was previously isolated from naturally infected farms depending on mortalities, clinical signs and PM lesions and biochemically identified and molecular screened for detection of virulence genes. Hematological, biochemical and Immune parameters revealed that all immunostimulant supplemented groups were significantly better than control and antibiotic groups. Histopathological examination within 7 days post challenge revealed necrosis of internal organs, inflammatory reaction, associated with hemosiderosis in positive control and antibiotic groups, but protection were higher in immunostimulant groups. In conclusion, the addition of immunostimulants especially garlic, Echinacea purpurea and yeast to the diet of O. niloticusfrys could improve growth performance, fish survival, immunological parameters. Further, they could be suggested as an effective alternative to antibiotics with respect that Echinacea extract is the most potent one of them.