On the background, I agree that black is absolutely the best as it makes the depth 9front to back) disappear, fish prefer it (yes, they do distinguish colours) and it will enhance the colours of fish and plants.
You need to track down some floating plants. Your gourami need those. By floating plants I do not mean duckweed and similar as it is not substantial enough. Water Sprite, Water Lettuce, Frogbit will work, or some of the styem plants will grow nice floating, like pennywort.
Glass cats...presumably this is the species Kryptopterus vitreolus. This is not a good community fish for a few reasons. They are very timid and shy, and any active swimmers may well cause them to stop eating. They need a group of at least five or six, or the same fate may occur (stop eating). They are mid-water predators and will "catch" food that floats gently in the current. A thickly-planted aquarium providing some swimming space with a gentle current is essential to calm this very timid fish. Floating plants will significantly assist in keeping this fish less stressed.