I have never seen a wound like or had one like that with it hanging out like that and if the Catfish did take damage that hurt it too I would get it looked at.
Jesus! That looks nasty. I had a wound like that from breaking up a dog fight. It was an inch by inch L shape, fat hanging out and all. I bought some iodine and cleaned it twice a day with that. Im obviously no dr. but keeping it clean and covered will save you lots of money at the dr's office.
Man, go get it treated by a doctor. Why take an unnecessary chance with your health? You may have a piece of the RTC's spine trapped in the wound. I believe in pinching pennies and all, but some things are definitely worth the money spent. I hope that you are ok, no matter what you decide to do.