You could go with a gourami.. either a dwarf or a honey gourami. They are very pretty. I have one in with my danios in my 20g long. He never messes with anyone, only to chase them away from the algae wafer when he wants a bite lol. If you get them, watch for signs of aggression though the first 24 hours or so in the tank... occasionally you can end up w/ one that is semi-aggressive. I had a neon blue one that killed neons, but this is not the normal experience for these type of fish and my other one is completely docile.