One thing I found out is, if the difference between the air and the water is too wide, it stresses them long term when breathing air. I always use a lid with these guys to make sure the air they breathe is the same temperature as the water.
They are not too fond of bright light, also, bright substrate that glows is stressing for them. they love floating plants in a dimmed environment. Like Gary said, If he's the king of that tank, research on their natural environment, and try to emulate it the best you can with what you can get. I agree on the temperature, while 78 is ok 80 is better. I don't know for how long you have him, but they are pretty shy fishes and need a good period of adaptation and might get spooked from interactions. if you can provide enough plants for him to hide in he will live it.
The big lines for a inviting Dwarf Gourami tank. Filled with a variety of plants, including Amazon swords, Java fern, Anubias, and floating plants like water sprite or hornwort. The plants create plenty of hiding places. They live in semi blackwater. Dark-colored substrates and driftwood to create a more natural, tannin rich environment with a slow water flow.
What happened to his left pectoral fin ?