Yes, we recently had surgery performed on a large Kohaku that we purchased at the Orlando show in 2005. It was a large tumor located in her chest area, between her pec fins and back a bit. Once removed it was the size of a softball. Dr. Amy Keiser (sp) specializes in fish and more specifically in fish surgery. She is also a consultant at our local Mall of America Aquarium display (can't remember the name of it).
Once the tumor was removed Doc Amy noted that her organs, more specifically her liver, was less than 1/2 the size it should have been likely because the tumor was taking up so much space that it crowded the organs. Once we saw the size of the liver, Doc Amy didn't hold out much hope for her recovery, but we decided that since she was in such good health prior to the surgery, that we would give her a fighting chance to recover. Doc said that if she surved the night, she had a little less then a 50/50 chance of making it. If she survived beyond that, every day her chances would improve greatly. We lost her on the 3rd day. There was no sign of infection. I had her in my Q-tank with Elbagin and a some salt to help the healing process. The incision was long because the tumor was so big in order to remove it. What Doc Amy did was to cut her open, and then she carefully and slowly ran her figures around the tumor working her way donw deeper and deeper to make sure nothing was attached or that the tumor wasn't encapsulating any vital organs. Once she was sure the tumor was totally free, she then simply lifted it out. Amazing to watch. She used a pump with water and anestetic (sp) flowing continuously over the gills which keep the fish under for about 45 minutes. She rested the fish in a large tray lined with foam to support the fish upside down. Under the tray sat a bucket from which the water was pumped up through a tube with was placed in the fish's mouth causing the water to flow over the gills. The water then traveled out from the upper tray through a tube the directed the water back to the bucket. But I live in Minnesota, not Canada!!