Can feeding on diet enriched with astaxanthin improve physiological responses of parrot fish (Cichlasoma synspilum ♀ × Cichlasoma citrinellum ♂) after exposure to water-born silver nanoparticle?

The aim of this study was improving antioxidant defense system and monitoring some plasma biochemical parameters of parrot fish fed on diet enriched with astaxanthin alone or in combination with bile salt after exposure to water-born silver nanoparticles (AgNPs). 200 parrot fish were randomly distributed in three different treatments as control, astaxanthin and astaxanthin-bile salt. The fish were fed for 90 days and then subjected to AgNPs 250 μg/L for five days and some plasma biochemical parameters were measured before and after AgNPs stress. The results showed that feeding fish with diet enriched with astaxanthin could cause significant reduction in the plasma levels of all studied oxidative enzymes in comparison to the other groups (P<0.05). AgNPs caused significant elevation in the levels of plasma oxidative enzymes in the control while such elevations were not visible in fish fed on astaxanthin (P>0.05). At the end of feeding trail, day 90th, plasma levels of hepatic enzymes, asparat transaminase and alanin transaminase were significantly lower in the astaxanthin - bile salt group (P<0.05); after AgNPs stress, the levels of the mentioned enzymes were significantly reduced in groups of control and astaxanthin, while such reductions were not observed in the group fed on astaxanthin-bile salt diet (P>0.05). The results of this study showed that astaxanthin alone or in combination with bile salt could improve some plasma oxidative and biochemical parameters of parrot fish when the fish were subjected to AgNPs. The positive effect of bile salt on astaxanthin function was observed on some parameters.