I have 2. The larger one is 13 inches. They can AND WILL eat tankmates that you think wouldn't fit into their mouths. I don't even want to list the fish that I've lost to their stomachs. And these aren't even elongated fish, but tall ones like a Datnoid (ouch...). I'm sure your catfish is making plans for the red devil as we speak. I also found them to be quite aggressive and territorial and would chase and bite other fish away from their territory. They're awesome!