Chemical components such as proximate and fatty acid compositions, ATP and its related compounds and free amino acids, of the splendid alfonsino Beryx splendens caught off the east coast of Izu, Japan, were investigated.

(1)　Splendid alfonsino samples caught in the summer had a significantly higher lipid content and significantly lower moisture content compared to those caught in the winter. The larger fish tended to have a higher lipid content and lower moisture content, although the differences were not of significant. There were no seasonal or size-based differences in the crude protein or ash content.

(2)　The major fatty acids in the total lipids were C16:0, C18:0, C16:1, C18:1n-9, C18:1n-7, C20:1n-9, C20:5n-3 (EPA), and C22:6n-3 (DHA). The composition ratio of the long-chain monounsaturated fatty acids, such as C20:1n-9 and C22:1n-11, was high at 2-6%.

(3)　Among ATP and its related compounds, the amounts of ATP, ADP, and AMP were consistently not greater than 0.1-0.3 μmol/g during storage at 5℃. As the storage duration increased, the IMP content decreased, while the HxR and Hx contents increased. The K-value increased during storage, reaching 12.8% and 56.8% after three days and nine days, respectively.

(4)　Although there were differences in the free amino acid content depending on the part of the body, high levels of anserine and taurine were found in all parts. Therefore, the efficient intake of health functional ingredients, such as anserine and taurine, is considered to be possible by cooking the entire splendid alfonsino fish.