I have a naso tang (about 4") and a blue hippo tang (about 3") in a 150 that I added on the same day. They get along fine. I have heard that it is best to either add all the tangs at once, or add the least aggressive tang first, and have also been told that when mixing tangs of different temperaments, it can help if your largest tang is also the mellowest. I might like to try my hand at an Achilles tang in the future, but I'm hesitant because I feel that might be pushing it in a 150... thoughts?