Hi and welcome to the forum
I wouldn't keep any dwarf gouramis because they can carry the Iridovirus and Tuberculosis (TB), neither of which can be treated and both diseases remain in the tank until it is taken apart and disinfected.
If you can get locally bred dwarf gouramis they should be free of disease, but anything from Asia should be avoided.
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There are plenty of other small gouramis (Honey, Indian banded, Licorice, etc) and these are usually free of the diseases.
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What are the tank dimensions (length x width x height)?
What is the GH (general hardness) and pH of your water supply. This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).
Do you have any floating plants in the tank?
Water Sprite (Ceratopteris thalictroides/ cornuta) is the best plant for labyrinth fishes (Bettas & Gouramis). It grows rapidly on the surface and has long stems and roots to provide shelter and break up territories. It can also be grown in the substrate.
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If you want gouramis, you normally have 1 pr (1 male and 1 female). You can keep a couple of females together but never have more than 1 male because they fight over territory.
And never mix Bettas with Gouramis because they really fight.
