Comparing effects of astaxanthin, turmeric and Spirulina platensis on growth, immunological parameters and coloration in white Oscar, Astronotus ocellatus

The present study aimed to determine the effects of four experimental diets on growth, immunological parameters, and coloration of the white Oscar, Astronotus ocellatus (Agassiz in Spix and Agassiz, 1831).  So that, 120 individuals, with an average weight of 7.5 ± 0.5 g, were randomly distributed in 12 aquaria (10 fish in each aquarium). The fish were fed with 4 diets as follows: pigment-free (as the control), astaxanthin, turmeric powder, and spirulina powder (100 mg kg-1) for eight weeks. At the end of the experiment, growth and immunological indices, as well as coloration were measured. There was a significant difference between control and the astaxanthin treatment in all growth indices except for condition factor (p<0.05). There were also significant differences between control and the spirulina treatment in the survival rate and growth rate; between control and the turmeric treatment in the increased length; and between control and turmeric and spirulina treatments in food conversion ratio (p<0.05). The results also indicated that there was a significant difference between the astaxanthin treatment and other treatments in lysozyme activity as well as between control and the spirulina treatment in terms of IgM level (p<0.05). However, such a significant difference was not observed in total immunoglobulin and total carotenoids (p>0.05). There was a significant difference between some treatments in the intensity of primary and secondary colors (p<0.05). The findings exhibited that all three types of pigments employed in this study could improve the growth factors, immunological parameters, and coloration of white Oscar; however, astaxanthin outperformed the others.