Recomendations usually run the gamut from 1 or 2 inches per gallon to feet per gallon. I would like to know how many yellow tangs I can cram in a hundred gallon tank on a permanent basis. I have a good protein skimmer, trickle filter, sand bed, and an upstream refugium. Right now I have 20 chromis damsels, five gobies, and some shrimp (including a pistol.) I would like to add ten to twenty yellow tangs in the small to medium size range all at once. I have adequate hiding places for all.