Effects of dietary supplementation of astaxanthin on growth performance and pigmentation of the carcass in rainbow trout, (Oncorhynchus mykiss)

The present study was conducted to evaluate the effects of different dosage of the astaxanthin on the pigmentation of the fish fillet and growth parameters and survival in rainbow trout (Oncorhynchus mykiss). Three treatments and the control in three replications have been performed in a completely randomized design plan with 40 fish (100 gr.) for every rearing tank. The fish of rearing tanks were fed during 8 weeks based on 2% of the biomass by the fish feeds treatments containing 30, 60 and 90 mg/kg astaxantin and one control feed without any astxanthin addition. At the end of experimental period, four fish of every rearing tank were randomly selected to assess the degree of the fillet pigmentation based on L.A.B colorimetric system measuring. No significant improvements of FCR or survival rate were observed between the treatment groups (P>0.05). Results showed the pigmentation in the treatments of 60 and 90 (the red (*a) parameter) has a significantly different value compared to the control and the other treatment (P<0.05). Results suggest that the 60 mg/kg astaxanthin was the best and economical concentration to impart the desirable flesh coloration.