Japanese foxes mainly feed on small mammals, birds, insects and berries. They will also occasionally prey on fish, especially when food is scarce. The living environment of saltwater fish is completely different from that of Japanese foxes. They live in vast oceans and their eating habits vary depending on the species. Some marine fish are herbivorous, feeding on plankton such as phytoplankton; others are carnivorous, preying on other small marine organisms such as fish, crustaceans or molluscs.

So, not all marine fish eat insects, and the diet of marine fish depends on their species. Depending on the ecological environment, it may include plankton, small fish, crustaceans, etc. Although both organisms may prey on insects or small invertebrates in some cases, this is not their primary food source.