I currently have a 2 yr old fancy goldfish in a 10 gallon tank with a sufficient capacity power filter.
The fish has typically been fed flakes, and often will float upside down for a little while after feeding but then right itself.
About 3 weeks ago this happened, but it has not been able to right itself. The tank maintenance has been performed correctly, and ammonia levels are too low to cause poisoning. I've heard about some public aquariums using syringes to aid in deflating the swim bladder, though looking at the anatomy of goldfish it looks as though the swim bladder is more on the top of the fish and this one is floating upside down. The fish has been fed peas, but that isn't working and he eats pellet food now (though he can't eat them on his own, we have to hold him and place the food practically in his mouth). It has been fasted for several days as well.
I have read that goldfish lack a connection between their intestines and their swim bladders, so my thought is that there could be something else wrong with him. I treated with Maracyn to prevent infection as his skin started to bleed where it was exposed to the air for long periods of time.
Tomorrow's course of action will be to remove the Maracyn, treat with copper sulfate (as I've found this to be a more effective anti-biotic), add aquarium salt, and aerate the water.
Does anyone have any suggestions to add/subtract to this course of treatment?