Sonya, from Highcroft Veterinary Group in Bristol, said: "Nemo was initially a referral, a little fish sent from Buckinghamshire to come and see us as another practice who did not want to do the surgery.
"We accepted it and the owners saw my colleague for a consult and decided to go ahead with it.
"Nemo is doing really well - he had a massive lump on the side of where the neck would be and it was looking the same size as the fish itself."
The surgery took about 45 minutes and Nemo was ready to return home to his owners after a couple of hours.
Despite the success there was a moment of panic during the operation.
Sonya said: "It was difficult keeping him asleep and alive - there was a hairy moment when his heart stopped but we managed to revive him.
"We kept Nemo asleep by putting a syringe into his mouth and gills. We had to keep oxygen in system."
But Nemo is now back to normal and enjoying life.
Sonia added: "He is just a little gold fish - five years old we believe - taken on by owners.
"The owner phoned up and said he was completely back to normal and doing really well."