Goldfish are omnivorous and their nutritional requirements are different from those of tropical fish. You should always feed your goldfish with food that is prepared especially for goldfish such as Top Fin Goldfish Flake Foods or Pro-gold Fish Food.
You can vary the diet of your goldfish by adding some cooked and peeled peas, boiled romaine lettuce or boiled spinach, small pieces of hard boiled eggs. Other foods that your goldfish can enjoy on occasion are earth warms and dried red worms.
Feed your goldfish once or twice a day. During the first few days watch closely to see how much food your goldfish consume within 3 minutes. This is the amount you need to feed them with every feeding.
Avoid over-feeding your goldfish. Goldfish love to eat and may seem happy enough to eat more and more. Yet, food leftovers, as well as fish droppings, will soon harm the water quality in your goldfish tank.