It finally got warm enough today to check out my pond and prepare for Spring cleanout to only find this thing protruding out of my koi. I'm assuming it's fungal due to coming out of the winter months but any suggestions would be greatly appreciated. I've never experienced this type of lesion before so I don't have a clue on how to treat it. BTW, the fish is acting normal and eating. He appears to be the only one with it.