Information is limited concerning variation of the δ¹⁵N with growth in marine organisms and consequently the effect of growth of marine biota on the δ¹⁵N is not yet well understood. The δ¹⁵N in 26 species of marine fishes taken from Japanese coastal waters together with 4664 stomach contents of these fishes were examined to investigate the effects of food habits and growth on the δ¹⁵N. The mean δ¹⁵N for two species that fed mainly on large-size fishes and six species that fed mainly on small-size fishes were 14.5±1.0‰ and 12.8±0.7‰, respectively. For five species that fed mainly on decapod crustaceans, two species that fed mainly on zooplankton, and three species that fed mainly on benthos (mainly Polychaeta), the δ15N were 13.0±0.7, 9.7±0.9, and 12.2±1.2‰, respectively. The mean δ¹⁵N in the species whose prey were mainly fish or decapod crustaceans was about 3-5‰ higher than the species whose prey was mainly zooplankton. Within the four species that shift their food habits with growth to higher trophic level, the δ¹⁵N significantly increased with growth in one species (Pacific cod), while not significant increase in the δ¹⁵N with growth in the remaining species.