What kind of surgery? Wow.We cut our holiday short by 4 days and came home because the friend house sitting for us told us there was problems with the fish. I've also performed minor surgery on a couple of fish when all other options had been exhausted (and both fish are still alive now).
A month getting my oranda goldfish better which my partner got me, she had brown patches on her belly underneath, plus swim bladder, antibiotics a month of daily water changes, she pulled through, but i still to this day have to keep her on a good diet.