Looks like a brown bullhead to me. They can vary in color accordingly to location, habitat, season and spawning. Here in my neck of the woods, I've only seen one's colored like the one you posted...maybe someone else has more, or something different to add. I've heard stress can cause the purplish color and or the blotchy-ness changes, and sometimes it occurs during the spawn, again...this is hearsay.
We catch a lot of catfish here; chanel and bullhead. It seems that there is no set color for cats. they come in grey, purple green, black and white, and tan. Some are plain and others are spotted, but they all taste good.
