They go by many trade/common names. They used to be called brown puffers, but nowadays I've heard many places across the U.S. that call them black river puffers. This species are inactive lurker fish. Mine stays under the same driftwood all day. If you provide a lot of cover, then he will hide in different areas. He will try to hide and try to ambush the cray if he has not already strike at first.
edit: your tank looks very bare. He looks like he has nowhere to hide, so he is just sitting in the corner of the tank. The white spots indicates stress because they are normally black.