I was gilled once. That kind of thing happens when someone in a lab coat asks you to help them out with an experiment. It started off okay. Swimming in a lake next to the reactor core was very relaxing. There were six eyed carp, four legged Alembic bass, and invisible trout. They wouldn't let me in their schools, however. I kept sneaking in, trying to see what they were working on. Sometimes, I'd see a complex diagram with the title, "World Domination", but they'd quickly cover it when they saw me.
Unfortunately, they never had the chance to carry out their plans because we were visited by the Gorton's fisherman. He dredged the lake and caught us all. I was immediately discarded on the beach.
After flopping and gasping for a few moments, I remembered to breathe normally. I walked into the lab and found the kid with the lab coat. It took some convincing, but he finally agreed to get rid of the gills. The horse tail was a complete surprise.
HTH.