Gourami Nest Building

Yes it is. They are closely related to bettas and they seem to behave very similarly.


Since male bettas are so aggressive towards females they can't be kept together except for while actually spawning, so they are kept without females, usually on their own. Male bettas build bubble nests all the time. In the wild male bettas have territories that they defend against other male bettas. They build bubble nests in the hope that an egg-full female should happen along so they are ready. Since male dwarf gouramis treat females similarly to male bettas (just not quite as aggressively) it is safe to assume their instincts about bubble nest building are the same.

My current male betta builds bubble nests non-stop. When I destroy it during a water change, he just builds another.

He may calm down or you may have an extra aggressive gourami that won't. It could be all tied up with territorial issues. If he's building a bubble nest, he has staked out his territory and he may well see the rainbows as invading his space.
If he doesn't settle in a few days, he probably won't.