My TSN does it mostly when I feed scallops. He gulps them too fast and a backup occurs. Try feeding larger items like shrimp and wait 1 minute in between each one, Also try Hikari Massivore delight. I havnt seen mine puke those up yet.
''i feed it guppy more than 1 inch and koi 4 inches! eat anything in sight! he's now more than 20 inches...and it have a duck-bill nose a perfect nose like duck......i feed it 1 time per 1 day....''
''when he was a little cat ...he's doing fine!..''
I had a rtc some years ago that would barf at least once a week i think it was the lunch meat i was feeding it really liked bolonga i did't know how to properly care for mine when i had it but it sounds like u are feeding your catfish right maybe u gave him to much to fast feed him 1 shrimp 2x a day see if that helps.