I have a 40 gallon tank with a dwarf gourami now. Just yesterday the angelfish and tetras were ok. I was shocked. So I went out and bought a goldfish and a betta to see if it was really the dwarf gourami that killed everything and it was! The gourami was chasing, nipping, and fighting with the betta. He was relentless, he then murdered the goldfish. I took the betta out before anything happened. Have you guys encountered such an aggressive gourami? What made him go nuts? I am going to get rid of him, but in all my years of fish keeping I never owned such a underrated fish.