Ive never had success with a school of yellow gangs, even with ample room. I did take care of a 90 gallon tank with a purple and a yellow that did fine together. I once put five tangs in a four hundred gallon tank, that fought amongst themselves until there was one left. Then another five in a 700 gallon tank that did the same. Some people have had success but it's still a risk, even when they are small.