Not to long ago I had a 400 gallon with the regal, powder blue, and yellow. I loved how much room my fish had and always considered that size to be the right size for tangs. Since then, I parted with all but the yellow tang, a few clowns, damsel, and coral beauty. I have them all piled into a very nice 110 acrylic. I really feel with the rock that the 110 is too small for my one tang. My next tank will be atleast 500 gallons and I plan on getting a school of Yellow Tangs. I have a 180 freshwater and by looking at it, its about the minimum size for a yellow tang to be happy. Just my thoughts.