I don't think he's going to last much longer. He's not moving much, and he hasn't eaten today. The wound just seams to be getting bigger and not healing. His breathing is rapid, and he goes to the surface for breaths much more often than when he was healthy. All the other fish seem just fine, and water conditions are good. Could this be Dwarf Gourami Disease? I read it can cause some sort of wound but I found no pictures, but he is lasting way longer than I thought possible.
Wouldn't you like to beside the seaside?