Effects of Fishmeal Replacement with Spirulina (Arthrospira platensis) and Sargassum ilicifolium Meal on Growth and Health Indices of Asian Seabass (Lates calcarifer) Juveniles

The influence of dietary fishmeal (FM) replacement with a mixture (1:1) of spirulina (Arthrospira platensis) and a brown seaweed (Sargassum ilicifolium) in Asian seabass (Lates calcarifer, 45.0±0.2) performance was evaluated. Dietary FM was replaced with the algal mixture at 5 (MIX5%) and 10% (MIX10%) and a diet without algal mixture served as control group. One hundred and thirty five L. calcarifer juveniles were stocked into nine 300-L circular containers (15 fish/tank) filled with seawater (salinity = 46.0±0.2 g L^-1; temperature = 31.5±2.5°C) with 80% daily water exchange rate. Each dietary treatment was conducted in triplicate. The experimental feeds were offered to fish thrice daily up to satiation for 60 days. Fish in MIX5% group had the highest weight gain (approximately 12%) that was associated with higher feed intake compare to the control. Viscerosomatic index was reduced in fish fed MIX10% diet compared to control group (8.6 vs. 7.6%). Amylase, alkaline phosphatase, total protease and trypsin activities significantly increased in fish fed MIX5% group (P<0.05). Liver superoxide dismutase activity (36.1 U/mg protein) and glutathione (33.3 µmol/g tissue) level increased in fish fed MIX5% diet. MIX5% group had higher white blood cell counts than other groups. Plasma cholesterol decreased (approximately 20 mg/dL) but plasma calcium content increased in fish fed algal mix-supplemented diets (P<0.05). Plasma triglycerides, total protein, globulin, and alkaline phosphatase decreased in fish fed MIX10% diet. Based on the above-mentioned findings, dietary FM replacement with micro- and macroalgae mixture at 5% is recommended for growth and improving health status in L. calcarifer juveniles.