Originally Posted by princesuhaib
watchmen goby + pistol shrimp
longnose hawk fish
clownfish (not sure what type) sadde back or regular nemo or maroon (yes maroons are the most aggressive)
royal gamma dottyback
I have my doubts about the Copperband, because adding this fish to a 75 gallon tank with an established Yellow Tang is going to be stressful. Copperbands are not an easy fish to keep, and you would probably be best to simply nix this fish from your list.
The Royal Gramma, Jawfish, Blenny, and Wrasse could all be added at the same time. I would suggest waiting at least 3 more months before purchasing these fish, to allow more time for your copepod and amphipod populations to spread. A refugium would increase your chances of success with these species.
I would skip the Mandarin Goby as well. You won't be able to sustain this fish in an aquarium as small as a 75 gallon tank. Just don't even try. Not even if....
I would also be cautious when adding the Hippo Tang. It should do fine in your tank, but the Yellow Tang will express some dominance. To reduce the risk I would add other fish at the same time. A small school of Chromis and the Long Nose Hawk could be added simultaneously with the Hippo. This will help to spread the aggression out from the Yellow Tang.
On the subject of the Tang, I would suggest feeding the aquarium about 30 minutes prior to adding new fish. A full fish is less aggressive. Also, feed from multiple locations within the tank to spread out the feeding zone, which will reduce the territorial tendencies of fish to become dominant in one specific area.
Finally, when you add the Hippo Tang, do not panic. Within 30 seconds of adding this fish to the tank you will think it is dead. It will fade in color and lay in one spot on the bottom of the aquarium. It may not move for 12 to 36 hours. Do not panic. Just leave it alone.
I also suggest multiple daily feedings, as frequent as every 2 to 3 hours, for the first couple of days after adding a new fish. This helps the fish become more aware of the feeding habbits in your aquarium and fish such as the Hippo are likely to begin feeding sooner. Just keep the feedings smaller in size until you go back to your normal feeding routine.