I have a couple of Electric Green Barbs that are sometimes agresive. I also have two red ones and they seem to get chased a lot by the green ones. I've read that these green barbs should be kept in groups of at least five but I don't know if I would be stressing the tank to add a few more. I have a 29 Gal tank with two fluval 30's and lots of air going throuout the tank. I also have 3 small zebra's and 5 baby cory's. Would I be crowding it if I added two more barbs? Thanks!