Culture of spirulina fusiformis and its evalution as a proein source in the diet of entroplus suratensis

Abstract

In the present investigation, suitability of Spirulina fusiformis as a dietary protein sources in E.suratensis was evaluated.The study was carried out on two aspects; (i) culture of the alga and (2) biological evaluation when incorporated in the diets. Among the different culture media tested for the culture of spirulina, Zarrouk medium was found to be the best followed by CFTRI medium. The rural waste medium and improved CFTRI medium also supported good growth, though at significantly lower level when compared to zarrouk medium and CFRI medium. In mass culture experiments, it was found that algal growth in rural waste medium was significantly higher than that in sewage medium.

Biological evaluation was done by incorporating spirulina as the sole source of protein in diets fed to E.suratensis fingerlings. The diets were formulated at different levels of protein (20-50 %0. Best values of SGR, FCR, Apparent protein digestibility, PER and PPV were recorded at 35% protein. When compared with a fish meal based control diet, significantly lower PER and PPV values and higher FCR values were obtained with the spirulina diets, though significant difference was not observed in the survival rate.

The effect of substitution of fish meal protein with that of algal protein was studied by gradually replacing the former by the latter in practical diets for E.Suratensis fingerlings. The results showed that replacement of fish meal protein upto 50% with spirulina protein in the diet of E.suratensis did not affect the growth performance and food utilization . Thus spirulina fusiformis seems to be a useful partial protein source in the diet of E.suratensis and its inclusion in the diet can replace 50% of the fishmeal protein which is of much economic importance as far as aquaculture industry is concerned.