The Goldfish Sanctuary
My fish refuses to eat!
It is first important to determine if your fish is feeding normally. Most often, goldfish are good eaters and are not too shy about eating. However, a more timid fish may be at a loss during feeding time, and so fish should be observed during feeding to make sure each gets a share of the food. In general, if a fish is rather smaller than his tankmates, he may not get as much food, not because he is unwilling to eat, but unable to eat. If a fancy goldfish is kept with more common varieties, the fancy goldfish may be unable to acquire adequate food. Extra effort on the part of the keeper can often alleviate this trouble, with separation for the fish in question if necessary.
Sometimes, goldfish will simply decide they do not like a certain food. It does not matter that other goldfish eat a certain food... yours is unique, and will decide this for himself. You may in this case see your goldfish 'tasting' a food and then spitting it out in a few seconds. In this case, other foods may be tried. It is usually not long before you find one that your goldfish will like. In general, goldfish are not very picky at all, and eat just about anything. When your goldfish becomes hungry enough, he will eat (and it is not uncommon for a goldfish to resist eating for three days or more!).
A goldfish who will not eat or does not eat as much as usual (especially when being fed foods that are normally accepted) may well be suffering from a disease. The keeper should be on the watch for other symptoms, and should consult a vet or petstore if in doubt.