You might also consider that many dwarf gouramis, particularly the ones with the gorgeous bright colours, have a distressing habit of dying suddenly for no apparent reason. Symptoms are non existent.. one day they will be fine, the next lying on the tank bottom or over a plant stem, and the day after that, they'll be gone. It's very disturbing.
They also need a very quiet tank, next to no current in the water, with many plants, both in the substrate and floating, for hiding places and shade. They don't want tank mates that swim fast or may be at all pushy toward them.
I'm not sure why they are so hard to keep, but they seem to be quite fragile. It's a shame because they are so very pretty. I really like them, and once tried quite hard to breed them. But I could not keep enough of them alive long enough to have any success and I eventually came to the conclusion that whatever the problem is with them, it's one I did not want to continue to deal with.
This is not to say you cannot keep a DG.. only that many of them do not seem to last very long. It may be due to inbreeding, or how they are farmed, or some other stress factors.