As has been said before, the tank is entirely too small for a goldfish; I've had some goldfish that would not physically fit in a tank that size. They easily grow to 6+ inches. Three is not old age as they regularly live to 10 or even 20 years old when given proper housing. There are a lot of myths out there about goldfish; their short lives and small size are two of the biggest.
Your fish is having swim bladder problems. These are quite common with fancy goldfish and goldfish kept in poor conditions, but I don't blame you for it as most pet stores just don't understand goldfish care. Feeding a pea will not help as it is not a digestive issue.
That being said, the only way to help your fish is to get her a larger tank. Since I see she's a common goldfish (doesn't have that chubby body and double tail), she will need a 40+ gal tank. She still has some growing left to do. And with clean water and some good food she could live close to a normal life.
Your fish is having swim bladder problems. These are quite common with fancy goldfish and goldfish kept in poor conditions, but I don't blame you for it as most pet stores just don't understand goldfish care. Feeding a pea will not help as it is not a digestive issue.
That being said, the only way to help your fish is to get her a larger tank. Since I see she's a common goldfish (doesn't have that chubby body and double tail), she will need a 40+ gal tank. She still has some growing left to do. And with clean water and some good food she could live close to a normal life.
