Hi, I currently have 8 red platies and 8 zebra danios in a 55 gallon tank. My LFS is getting an order of rainbow fish this week and I would like to stock a small school. They expect to get some Australian (Murray River), Red Irian, Turquoise (Lake Kutubu), and Boseman's rainbow fish. I was wondering if I could get 2 each of 3 different types, or 3 each of 2 different types, or if I have to get a school of 5 or 6 of all the same? Thanks!