Is anything poisonous about catfish

No, but they can inflict a wound that can become enflamed or infected. If you are ever finned by a catfish, make sure to clean the wound. If you are fishing in the ocean, use ocean water as a temporary cleaner. When you get home clean the wound. If you are fishing in fresh water, try to clean it with bottled water temporarily until you can get home to clean it properly.

If you get finned so badly that the bleeding won't stop. Go to the nearest Emergency Room. The fin might have hit a blood vessel.