Feeder fish is the generic name for certain types of inexpensive fish commonly fed as live prey to captive animals such as sharks, turtles and some other fish such as oscars.

The species of fish usually sold as feeder fish are invariably some of the easiest fish to rear and breed, such as goldfish and guppies. Typically, these species are tolerant of overcrowding and have a rapid growth rate. This makes it easy for fish farmers, retailers, and hobbyists to maintain large populations of these fish that can be sold at a much more affordable price than the more delicate ornamental fish that require better conditions.

In some cases, species of predatory animals, typically large fish such as catfish and cichlids but sometimes also animals such as freshwater turtles, are provided with feeder fish because they accept them more readily than alternatives.

The major varieties include:

The comet goldfish can be distinguished from the common goldfish by its long, single and deeply forked tail fin. Comets with yellow, orange, red, white, and red-and-white coloration are common.

Artemia is a genus of aquatic crustaceans known as brine shrimp.  The ability of the Artemia to produce dormant eggs, known as cysts, has led to extensive use of Artemia in aquaculture.

Just as their name suggests, livebearers are fish that give birth to live, free-swimming young.

Ghost Shrimp, also known as Glass Shrimp, are excellent scavengers. They are inexpensive and efficient aquarium cleaners that will actively search for any kind of left over food in your aquarium.  

Rosy Red Minnows (Pimephales promelas) are actually fathead minnows, but due to a genetic mutation they are a light "rosy" color.

Tubifex worms are often used as a live food for fish, especially tropical fish and certain other freshwater species.