Well i definatly cant do four. although, i've always had success going a little heavy on the fish load. (good protein skimmer, weekly 10% water change, and a boatload of live rock). However I already have a pair of maroons one very large, one medium. Pair of neon dottybacks, full grown. pair of blue damsels one medium one small, and a medium dragon goby. I have over 300 lbs of lr crammed into my 100 gal. if i should include shrimp let me know. i was hoping for 3 small yellow tangs. probably pushin it. however i always say there are no rules in saltwater, just guidelines. Like for instance in the past i have had luck keeping 2 different angels in a tank, friends of mine have kept 3 and 4. well im rambling. Guess im out of luck on the tangs. maybe ill just do one.