Muscle nutrition analyses of two marine eels Conger myriaster and Muraenesox cinereus across different coastal regions of China

Conger myriaster and Muraenesox cinereus are commercially important species in East Asian fisheries, yet their nutritional profiles across diverse coastal habitats remain poorly characterized. This study systematically analyzed the muscle nutritional composition of these two eel species from various coastal cities in China. Samples of C. myriaster were collected from Dalian, Qingdao, and Zhoushan, and M. cinereus were sampled from Zhoushan and Xiamen. Nutritional indicators, including proximate composition, amino acid levels, and fatty acid contents, were investigated. The results revealed that C. myriaster had a notably high content of crude fat (12.22%) compared to most marine fish species along the Chinese coast, while the crude fat (3.21%) of M. cinereus showed no apparent advantage. Both species exhibited relatively high levels of polyunsaturated fatty acids (2.501 g/100 g for C. myriaster and 0.717 g/100 g for M. cinereus ), with particularly high concentrations of EPA (0.465 g/100 g and 0.202 g/100 g, respectively) and DHA (1.223 g/100 g and 0.281 g/100 g, respectively), and their fatty acid compositions adhered to WHO standards. While the crude protein (16.78% for C. myriaster and 18.40% for M. cinereus ) and amino acid levels (14.98 g/100 g and 13.58 g/100 g, respectively) did not exhibit marked elevations, the amino acid proportions of both species met the FAO/WHO standards for high-quality proteins. These findings indicate that both C. myriaster and M. cinereus are valuable sources of dietary fatty acids and proteins. Furthermore, significant regional differences in nutritional composition were observed, likely influenced by environmental factors and diet structure. These results not only provide a scientific reference for further research on geographical nutrient differentiation incorporating environmental parameters, but also offer data-driven support to the eel aquaculture industry for optimizing farming conditions.