Never had them. They almost sound like southern catfish. They can get big, but the ones that I have had tended to be the smaller commercially grown ones. The big ones are sometimes caught using a technique called "Noodling". It almost sounds like a technique that an Aussie would use. You could look it up, or I could give you some links. That is one way of fishing that I will probably not ever do.
I've seen noodling on TV, we've evolved past that.