floating fancy goldfish

Question
Over the past few weeks my two goldfish (Ryukins) have started to float to the top of the tank, unable to stay in the middle or bottom.  When they try to swim anywhere else it is labored and they typically give up and float back to the top.  This happened with my previous goldfish of the same variety and eventually they died.  From what I've been able to find so far it could be due to bad food damaging their swim bladder, so I was instructed to get a different food.  This new food is helping, but not a lot.  I am now only feeding them once per day, minimally, as told by the "fish expert" at the fish store.  Any advice is greatly appreciated, as I'd really like to keep these guys alive!

Answer
David,

It sounds like swim bladder disease. The swim bladder helps keep the fish upright. Fast them for 2 days. On the third day cook some frozen peas. When the peas cool down, remove the outer shell and throw it away. DO NOT feed them the shell because they cannot digest it. Cut the peas up in small bite size pieces and feed the pea to the fish. After feeding them fast them again for 2 days. This should help them get better. Swim bladder disease is mainly caused by over feeding. I think you should be fine the way you are feeding them now. If you have any more questions, feel free to ask.