Food habits of juvenile devil stingers Inimicus japonicus and their changes with growth in the Zostera marina seagrass bed in Mano Bay, Sado Island [Japan]

Stomach contents of the devil stinger Inimicus japonicus collected from Mano Bay, Sado Island, were examined to clarify the changes in their diets with growth. Juveniles of devil stingers [ 5 cm total length (TL)] settled on the Zostera marina seagrass bed from August to September, and grew up to 10 cm TL at age 1 and 15 cm TL at age 2. Although devil stingers were piscivorous from the stage of settled juveniles, the species composition of consumed fish changed with their growth. Age-0 devil stingers including settled juveniles fed exclusively on gobies such as Gymnogobius heptacanthus. Over 12 cm TL, however, flatfishes such as released Japanese flounder and marbled sole, network filefish, and dragonets began to increase in their diets; and devil stingers 18 cm TL fed mainly on fishes other than gobies. This diet change seems to result from the preference toward larger prey by devil stingers as they increase in size.