The problem with trying them small is correctly sexing them. I tried to put two in at the same time that were nearly identical in size at about 3" and they fought worse than any fish I have seen. I knew that one would eventually kill the other one so I pulled one out and put it in another tank. The LFS told me that both must have been males but I can't verify that yet as it has only been about a year and neither of them has developed a defined streamer due to their still small size. A very large tank may help but my large tank didn't help me as they looked for each other to fight. Both of mine are very passive with my other tangs but they hated each other.