i have my dolphin in with some colorful peacocks right now. I have also kept him in with some of my haps , both ways worked out good. My dolphin was very slow growing compared to other similar species and my male is fairly aggressive, had to take it out and play musical tanks once it hit 4 inches to find a setup that worked ok for him. He was a chaser, never really harmed anything but would chase everything around and want to mate LOL. I got mine at petco last year, never saw any there again and wished i had bought more of them LOL. Not sure who would be good to order from online now, have not ordered for a long time...just be sure to pick one who has good reputation and where people say good things...