Effect of astaxanthin on colour,stress tolerance and haematological parameters of koi carp

Abstract- The shell waste of deep sea shrimp (Aristeus alcocki) was extracted using acetone as solvent. A total of 193.7µg astaxanthin was procured from one gram of dry shell waste. Four different experimental diets T1, T2, T3 and T4 were prepared by respective incorporation of 0ppm (control), 10ppm, 25ppm and 50ppm shrimp-extracted natural astaxanthin into powered commercial fish feed of known composition. A feeding trial of 21 days was conducted in indoor FRP tanks with four treatments and four replications in each. The water quality parameters such as DO2, pH and ammonia level were maintained at optimum level. At the end of feeding trial fishes were anaesthetized by clove oil and the blood was pooled into eppendorf tubes for analyzing haematological parameters. After blood collection fishes were sacrificed ethically and liver was collected for the analysis of specific activity of antioxidant enzymes such as SOD, CAT and GPx. Another lot of fishes were exposed to 5ppm ammonia stress for 24 h and again specific activity of enzymes and blood parameters were evaluated. Specific activity of all enzymes decreased significantly before stress compared to control. Stress increased the activity of the enzymes significantly but the rate of increment was less in astaxanthin fed fishes. The reduction and increment in specific activity of enzymes before and after stress showed dose dependent pattern. Before stress blood parameters like RBCs, PCV and Hb decreased in astaxanthin fed fishes compared to control but it was not significant. WBCs increased in T4 compared to control but not significantly. Ammonia stress caused further reduction in RBCs, WBCs, PCV and Hb but the rate of reduction was minimum in T4 compared to control and other treatments. This means that shrimp-extracted astaxanthin helped the fish in maintaining all blood parameters at optimum level. Colour changes with respect to feed was qualitatively assessed by a panel of judges. Score card was prepared according to hue of the colors of fishes. Highest score was received by T4 whereas lowest score was assigned to T1. The optimization of blood parameters and specific activity of antioxidant enzymes against stress and consequently, the improvement of colour of koi carp demonstrated that deep sea shrimp (Aristeus alcocki) waste can be a good source of astaxanthin to be used as feed supplement for improving colour and stress tolerance in ornamental fishes.