Forage fish, also called prey fish or bait fish, are small pelagic fish that feed on plankton and other tiny organisms. They are preyed on by larger predators, including larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding. They include particularly fishes of the order Clupeiformes, but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.

Bait fish are small-sized fish caught and used by anglers as bait to attract larger predatory fish, particularly game fish. Baitfish species are typically those that are common and breed rapidly, making them easy to catch and in abundant supply.