No more than 5? That's what I told myself too, but my tank is less than half the size of yours. I guess pending on what 5 you're looking at that could still fill up quick. Danio's might be worth a shot but at the size most of your fish are right now the danio might be a nice snack. However, they are extremely fast so they could maybe stay out of the way. If you did get em, I would get 5 or so to see if they last, but you could easily do like 10 in your big tank. Big groups look super cool! Good luck man!