What type of catfish is this?

I have a catfish but don't know what type it is. Its main color is brown and has spots that look like a cheetah. I bought it and it was the size of my pinkie finger but is now about the size of the palm of my hand. It has big fins that are clear and with black lines. Also my pictus catfish fights with it and doesn't want it to eat. The unknown catfish hides under my treasure chest all of its life.