Synergistic impacts of dietary supplementation of taurine, lysine and methionine in low fish meal diets on the growth performance, health status and liver histopathology of meagre<i> (Argyrosomus</i> <i>regius</i>)

This study evaluated the synergistic effects of taurine, lysine, and methionine supplementation in low fish meal (LFM) diets on the growth performance, health status, and liver histopathology of juvenile meagre (Argyrosomus regius). Experimental diets were prepared compared to a high-fishmeal control diet (HFM) and a low-fish-meal basal diet (LFM), which was supplemented with combinations of taurine, lysine, and methionine. Supplementing LFM diets with taurine, lysine, and methionine significantly improved growth performance (P < 0.05). Specifically, the LFM+TLM (taurine + lysine + methionine) diet achieved growth performance statistically comparable to the high fish meal (HFM) control diet (P > 0.05). Hematological analyses revealed that supplementation with taurine, methionine, and lysine significantly increased hematocrit and hemoglobin levels (P < 0.05). Histological examination of liver tissue showed that amino acid supplementation (particularly taurine) reduced liver lipid accumulation and improved liver health (P < 0.05). Moreover, total ammonia nitrogen (TAN) excretion was significantly lower in the amino acid-supplemented groups compared to the LFM diet alone (P < 0.05), indicating optimized nitrogen metabolism and enhanced environmental sustainability. Economic analyses demonstrated that supplementation with taurine, lysine, and methionine in LFM diets improved feed conversion efficiency and increased economic profitability. In conclusion, this study indicates that supplementing low-fish meal diets with taurine, lysine, and methionine can significantly enhance growth performance, health status, and feed efficiency. The findings highlight the potential of amino acid supplementation to optimize nitrogen metabolism, improve liver health, and reduce environmental impact, offering a cost-effective and sustainable feeding strategy for meagre aquaculture.