I mainly have more agressive fish, they all go good togeather though. I have two smaller oscars (one albino one wild) and one bigger one (red tiger) two baby green terrors Baby Arowana and baby Aligator gar. When I build the pond I plan on moving arowana gator gar and big oscar to pond. Then when the other fish get big enough i will either be considering a bigger tank as well where they might go but I might put them in the pond as well not sure yet. Despite being classified as agressive they all have seemed to go good togeather and don't fight much at all. I have anouther 55 gallon dedicated to a red devil which I have been afraid to introduce to anything else. I would love to have a payara and have been looking for one for a while. I'm dedicated to keeping my fish healthy and happy. Doing tank break downs and gravel vacuming every week.