Adding Tangs

[naesco]

IMO you should add them all together. You can get away with it only because you have a large tank.

You need to do it in the dark an leave the light out for a couple of days and the room darkened.
Avoid approaching the tank during this time or you will stress the new fish

Feed lots and in different parts of the tank

The idea is to get the fish used to each other.

Remember to feed garlic and selcon soaked food to build up the new fish and avoid ich

Remember the kole needs film algae so keep a side of your tank 'dirty"
Good luck