Investigating the effects of partial replacement of fish meal with spirulina and sargassum macroalgae on blood parameters in Asian sea bass

Abstract

Introduction: Fish powder is commonly used as a protein source in aquatic feed. However, due to the expansion of the aquaculture industry and the decline in marine fish catch availability, alternative sources for fish powder are becoming increasingly important. Algae has emerged as a potential substitute as it offers a cost-effective and easily produced protein source compared to fish meal. Additionally, an alga is less exposed to biological contaminants compared to fish, making it a suitable alternative for aquaculture. The present study aimed to investigate the effects of partially replacing fish meal with spirulina powder and Sargassum macroalgae on growth indicators, immune response, and digestive and antioxidant enzyme activity in Asian sea bass.
Material & Methods: A total of 225 Asian sea bass fry, weighing 45±2 grams, were randomly assigned to five experimental treatments, with each treatment being replicated three times. The fish in all groups were fed the experimental diet for a period of 60 days. The experimental diets for each treatment were as follows: Treatment 1 received 95% fish meal and 5% spirulina; Treatment 2 received 90% fish meal and 10% spirulina; Treatment 3 received 95% fish meal and 5% spirulina with Sargassum algae; Treatment 4 received 90% fish meal and 10% spirulina with Sargassum algae. The control group was fed daily commercial food containing 42% protein, comprising 100% fish meal.
Results: The results showed that, there was no significant difference in the amount of calcium, albumin, and cholesterol among the treatments after 60 days. However, significant differences were observed in the total protein, total globulin, glucose, and triglyceride levels among the treatments after 60 days. Finally, in terms of blood parameters, there was a significant difference in hematocrit levels between the 5% mix and 5% spirulina groups compared to the control group, with an increasing trend. The white blood cell count in the 5% mix group was also found to be increased compared to the other groups.
Conclusion: Overall, the results suggest that the concentration of spirulina in combination with sargassum less than 10% and use the right amount of both types of algae to get the best possible benefits for the Asian seabass.