African butterfly fish :D
They are amazing fish who can be surface aggressive but as long as you have floating plants(as in leaving rooted plants floating at first) they are fine, and once they are used to the tank mates they are usually pretty docile. . Also the betta must be big enough to not be eaten. My females where fine with my African butterfly and I'm keeping my knew one with my male beta Gabriel until he's off of crickets and eating flakes.
Hands down my favorite small species of fish. Another plus is they're living fossils, pretty awesome.