Sparkling Gouramis are tiny, 1.5cm absolutely tops and when you take into account the fact that they arent a fast or 'free swimming' sort of species, they just kind of bumble about, not moving much and will move from one shelter to another.
So providing layout is good (not just pebbles at the bottom but bogwood and plants or at least decor up to the top of the tank to allow them to move without feeling scared in the open) the sparkling gouramis should be just fine! (or pygmy gouramis)