Peas worked for a while with our swim bladder issue fish, but he did eventually succumb (at about five years of age). The depth of the water is ultimately the problem. Goldfish apparently only need water as deep as they are long (mouth to fin tip). Our shorter goldfish was the one with the problem. The longer ones are perfectly happy because the water is not too deep for them.

Goldfish only need shallow ponds, so this kind of makes sense. A deep fish tank is not their natural environment.