The gourami Trichogaster trichopterus (also known as Trichopodus trichopterus in some references is a popular fish with several different color variations that are very popular and well-known to aquarists. The "natural fish" is brown with faint bars and two dark spots on each side that, along with the eyes, give this fish one of its common names, the Threespot Gourami.
The Opaline Gourami has a silvery-blue body with darker markings. The markings often have a bluish tint to them. As with all variants of a species, exact coloration and pattern can vary between individuals.
Gouramis and other Anabantids (including the ever-popular Bettas and Siamese Fighting Fish) have an internal organ called the labyrinth organ that allows them to breathe atmospheric air in addition to using their gills. This is an adaptation to the rice paddies and stagnant pools in which these fish often live. All gouramis also have specialized pelvic fins that look like long filaments that they use to sense their surroundings.
Gouramis, like bettas, are bubble nest breeders. The males build floating nests out of bubbles that the eggs are deposited into until they hatch and develop into free-swimming fry. Breeding is fairly simple. Males and females can be differentiated by colors in many cases (males being more colorful) and male fish develop a dorsal fin that is elongated and ends in a point while females stay short and rounded.
These fish will accept a large variety of floating pellet and flake foods. Gouramis are generally suitable for planted aquariums, as they will not damage the live plants. As they get larger they can become slightly aggressive, particularly to other gouramis or in confined conditions. Tank mates should be chosen to able to handle this aggression. They do well with barbs, loaches, large tetras, and semi-aggressive cichlids. Dwarf gouramis are less aggressive and can be kept with smaller or more peaceful tankmates, or in smaller aquariums than their larger counterparts. Some species are highly specialized and may grow very large or need a very specific pH range or other water parameters.
I have a male Opaline Gourami in a 20gal. I have him with a Golden Gourami bought at the same time and same size, and (was 3) now only one blue dwarf gourami. The Opaline has become more aggressive as he's grown, I believe over territory more than anything. I purchased a smaller female opal, and they got along with her by terrorizing her whenever they wanted...
Recommend a larger tank, 55+. They LOVE live plants and dried bloodworms