I keep both of my bettas in community situations. One is in a 10 gallon with a small group of pure endlers. The other is in a 120 gallon community tank that includes neons, r5asboras, platies, mollies, gold barbs, rainbow cichlids and corydoras among other things. The one in the 120 needed to learn to respect territorial claims of the rainbow cichlids but his fins are growing back out now. The one with the endlers chased them a bit for a day or two until he figured out he couldn't catch them. Both are living well and are not pests in their tanks. They are no more aggressive than a typical tetra would be in the same tank.