Goldfish with swimbladder

Question
We're pretty sure our ranchu has swimbladder.  From early in our healthy main tank with great water quality he had difficulty swimming upright and it got progressively worse.  Now we have him in a separate, small tank, not filled to the top and he cannot swim.  He just lies on his back and occasionally makes an effort to move his fins.  He manages to eat.  He is definitely a sturdy type because he's been like this for over a month.

We have tried the standard approaches.  Epsom salt, starving him for 3 days or so, feeding peas and greater aeration.  

Is there anything else you can think of that might work?  At this point we are willing to take drastic action to save this little guy.  Thanks for any help you can provide.

Answer
Hello,

Is your tank heated? Although goldfish do not require heaters, increasing the temperature along with trying those treatments can help sometimes. Seventy-eight to eighty degrees would be good if you are able to adjust the temperature.

Another option is to try a broad-spectrum antibiotic such as Maracyn 1 & 2.

Sometimes, swim bladder problems never go away. If your fish ever gets to the point that it is unable or unwilling to eat, euthanasia might be the kindest option for your fish.