Hi Deb,
Catfish are known to do these types of things and yes they pay somewhat of a price for it. I wouldn't worry to much about your cat. Its important to keep the water very clean so infection doesn't take hold.
If you find in a few days is does worsen you can use some EM tablets, you should be able to find this in your local petshop.
Try not to worry to much, these things do tend to heal up by themselfs. Keep the water very clean for the next week.
Feel free to post back if you have any questions ....