I have a 20g tank with 3 guppies, 7 neon tetras, 2 albino cory catfish, one bristlenose pleco (they stay little) and one dragonscale, crowntail betta. He is white with red and black tail tips. I prepared the tank and added all the tank mates prior to purchasing and putting in my betta, "Oscar". They all get along, Oscar seems very happy, (probably pleased to be out of the little cup and in a 20g tank!). It worked really well. My neons did not eat right away either, yet now they are eating just fine. Turning off the light helps the neons to de-stress. Oscar is blowing bubles at the top of the tank and is the biggest fish in the tank. I think that helps too. There has been no fin nipping of Oscar by the other fish and no chasing of the other fish by Oscar.