The goal of the current study was to convert bioenergy from extracts of Chlorella marina, Sargassum muticum, Kappaphycus alvarezii and Ulva Lactuca (direct culture) to enrich rotifer Brachionus angularis, which was then fed to larvae of Asian seabass (Lates calcarifer). The larvae with an initial mean length of 4.1 ± 0.6 mm and weight of 0.40 ± 0.5 mg, were reared and fed with algal extracts-enriched rotifers for 15 days. Among tested treatments, rotifers enriched with S. muticum biomass consistently outperformed than other diets. Seabass larvae receiving S. muticum-enriched rotifers exhibited significantly higher final mean body weight (30.3 ± 5.2 mg), total length (12.5 ± 1.8 mm), specific growth rate (31.0 ± 0.2% day−1), and weight gain (29.92 ± 2.7%) compared to other tested diets. S. muticum’s fatty acid composition showed a maximal concentration of 26.936 ± 0.07% arachidonic acid and 18.143 ± 1.1% eicosapentaenoic acid. 43.3 ± 0.1% oleic acid (C18:1n-9), 36.2 ± 0.2% palmitic acid (C16:0), 9.2 ± 0.2% docosahexaenoic acid (C22:6n-3), and 8.7 ± 0.7% palmitoleic acid (C16:1) were found in rotifers fed a diet including S. muticum. The contents of 30.3 ± 0.3% docosahexaenoic acid (C22:6n-3), 20.6 ± 0.5% oleic acid (C18:1n-9), and 19.9 ± 0.7% palmitic acid (C16:0) in 2-dph seabass larvae fed S. muticum-enriched rotifers were considerably greater (p < 0.05) than those at 13 dph. The DHA content of 13 dph larvae fed a S. muticum diet was significantly higher (p < 0.05) than C. marina. Lastly, rotifers enriched C. marina and S. muticum fed to 13 dph larvae fatty acids were considerably higher (p> 0.05) than those fed to 2 dph larvae. Furthermore, S. muticum enrichment had a significant positive influence on larvae nutritional composition and fatty acid profile. Observed results indicates S. muticum extracts served a suitable dietary source for rotifer enrichment, thus enhanced the nutritional quality of live feed. Therefore, S. muticum extract can be considered a promising alternative for rotifer culture and nutritional enhancement in fish larvae rearing to scale up large level.