Looking through one of our books, I came across this:

The Simple Guide to Marine Aquariums- Chapter- A sample of Troublesome Fish.

Marine Catfish- " Commonly available and inexpensive, these fish are nevertheless extremely unsuitable for your tank. Though they are strikingly colored as the little babies sold in the trade, they mature into drab adults that no longer school. In fact, they get rather nasty while growing to their full length of more than 1 foot (30cm). They also possess venomous dorsal and pectoral spines and can be dangerous if not handled properly. Human fatalitites from the sting have occurred."

Hope that helps...