Stable isotope dataset of muscle tissue (δ¹³C and δ¹⁵N) and otoliths (δ¹³C and δ¹⁸O) of Mediterranean myctophids

This dataset contains raw stable isotope values of muscle tissue (δ¹³C and δ¹⁵N) and otoliths (δ¹³C and δ¹⁸O) from Mediterranean myctophid species collected along the Spanish and Catalan eastern coast. Variables include species identification, sample ID, total length (cm), total weight (g), muscle carbon and nitrogen mass fractions (%), C:N molar ratio, and otolith carbon and oxygen isotopic values (‰).