I have a three spot gourami, and now that you say that and I am thinking about it, maybe he is getting more stressed with the more fish we add to the tank. Except we had nearly 50 fish, mostly smaller ones, a little while back and he seemed fine. Then we had a little disaster, lost majority of the fish except the three spot gourami and a few others, but ever since then is definitely when he started being more skittish and shy. they seem to be one of the more sensitive species for sure given my experiences with them. I also live on the third floor of this apartment building and you can feel all my neighbors footsteps and ours of course, and i know he feels it and it scares him, I just feel awful.