This study was conducted to evaluate the effectiveness of enriched diet with astaxanthin alone or in combination with bile salt on some physiological Indices of parrot fish under water-borne silver nanoparticle stress condition. For this study, 200 parrot fishes (average weight 25.5±6.5g and length 6.34±0.43cm) were randomly separated in three different treatments including control treatment (basic diet), astaxanthintreatment (diet enriched with 4 g/kg astaxanthin) and astaxanthin-bile saltstreatment (diet enriched with 4 g/kg astaxanthin and 1200 mg/kg bile salts) fed for 90 days and then applied stress of silver nanoparticles whit doses of 250 ?g/l for five days. The results showed that fishes fed with of astaxanthin diet had the best main growth parameters in comparison to the other treatments (P 0.05). The time required for the fishes fed on astaxanthin and bile salts diet to achieve the highest pigmentation intensity was reduced one-third of the fishes fed with astaxanthin. The lowest plasma oxidative enzymes were observed in fish fed astaxanthin diet (P 0.05). After the stress significantly increase in the levels of oxidative stress enzyme were observed in the control treatment, while there were no significant changes in treatments of fishes fed with astaxanthin (P 0.05). Plasma hepatic enzyme have not significant difference in control between astaxanthin treatments at the 90 th day (P 0.05), both this treatments, showed significant reduction in hepatic enzyme levels after exposure to stress (P 0.05). There were no significant difference in the levels of globulin and total protein among the treatments at day 90 (P 0.05) and a significant reduction was observed in the control treatment s after the stress (P 0.05) but this reduction was not observed in astaxanthin and astaxanthin-bile salt treatments(P 0.05). Stress caused major histopathological alternation in the gills of the fish in all treatments, but the alternations in fishes fed with astaxanthin alone or in combination with bile salt were lower. In summary, the results of the study showed that astaxanthin treatment could improve growth indices in the parrot fish while the best results for pigmentation were achieved as combined with salt bile. Astaxanthin alone or in combination with bile salt could reduce gill histopathological alternations after the stress. So it can be conclude that astaxanthin alone or in combination with bile salt could improve some physiological characteristics of the parrot fish. Key words : blood parrot,astaxanthin ,bile salt, nanoparticles