Normally a true "white catfish" only live on the east coast because they need some salt and are in the rivers that drain in the oceans. Here is a good picture of one :
white catfish photo I've caught these before on the east coast, they really look alot like small blue cats, and they don't get near as big as other catfish. Most white catfish are this size in the picture, and usually bite like crazy around 5pm when the sun is dropping in teh backwaters, and if you get a 5 pounder then thats a giant.