my black neons arent aggresive at all, they are very active, they like to school with my cardinals sometimes, the danios are the ones who seem a little aggressive, they chase eachother around, and sometimes my cardinals, but they don't mess with my black neons for some reason. My tank is still growing, I really need some plants for the fish, I only have two live ones in there right now, but the fish seem to have fun, they love my new Emperor 400, since it puts out a nice current, I have the filter all the way to one side of the tank, so the other side is halfway calm so they can rest or whatnot, I'll put a pic up a little later.