The Puffer Forum

I've had my F8for about a month now. About 2 days ago a strange pink growth started showing up on his right pectoral fin between the fin and the gill. It is increasingly growing and now his underbelly looks reddened and swollen. He has absolutely no use of his right fin due to this growth. He's become increasingly lethargic as well.
He shares a 55g tank w/ another F*, 3 catfish, one chinese algae eater, some feeder guppies, and 3 placos.
Please help, I really don't want to lose him.

It sounds like a cyst. But I can't be sure. Can you take a picture and post it for us?

Also can you please answer the rest of the questions in red listed above. Water parameters etc.