[naesco]

Your tank is large enough to accommodate both and they are of different species.
When you add your tang do so when the tanks lights are off. You can add some food to the other end of the tank to keep the hippo occupied.

Add the yellow tang and then leave the room and keep the lights off for a day.

There may be some sparing but they will get used to each other.

Make sure you feed garlic extreme soaked food with added selcon to the nori you feed her to lessen the chance she gets ick.

The hippo needs meaty foods as it is the only non herbivore tang.

Now would be a good time to add another tang at the same time if you are considering it. Ad them together. I would recommend a powder brown A. nigercans (the one with the orange on it) Choose a plump healthy one that you see it eat. Clear eyes, no spots or tears. Inquisite. Just as interested in you as you are at the fish.

Good Luck