As a group, bony fishes have a diverse range of food preferences. Some are herbivores (plant-eaters); some are carnivores (meat-eaters); some are omnivores (plant- and meat-eaters); and some are detritivores (animals that eat decomposing plants and animals).

As a group, bony fishes can eat all sizes of plants and animals, from microscopic plant plankton to some of the largest marine animals.

Some of the animals common in the diets of bony fishes include: annelid worms, marine snails, mussels, clams, squids, crustaceans, insects, birds, amphibians, small mammals, and other fishes.

The amount of food a bony fish eats is directly related to its size, its metabolic rate, and the temperature of its environment.

Some bony fishes can go long periods without eating. Some freshwater eels (Anguilla spp.) can survive more than a year without food.

Some researchers have calculated food intake for some species.

Many bony fishes, such as mackerels and tunas (family Scombridae), seabasses (family Serranidae), and others are active predators. Like other predators, they often select weak, ill, injured, or dying prey because it is easier to catch.

Some bony fishes, such as anchovies (family Engraulidae) are filter feeders. They strain plankton from the water with gill rakers.

Many bony fishes, including catfishes (Family Ictaluridae) are adapted for bottom feeding.

A species' particular mouth shape and teeth are adapted to accommodate a particular diet.

Some bony fishes are quite specialized for feeding. Here are just a few examples: