While goldfish will eat crustaceans, insects, plants and smaller fish in the wild, those that are kept as household pets most often eat commercially made goldfish food. This can be safely supplemented with shelled peas, cooked vegetables, brine shrimp and blood worms.
It is important to feed goldfish food specifically designed for their dietary needs. Other fish foods contain protein and carbohydrates in amounts that may be too high or low to keep them healthy and thriving. Goldfish food commonly comes in flake or pellet form and should be fed as directed by the label. Goldfish will continue to eat as long as food is available, so be careful not to overfeed them.