Blue Fishing Lines

Can I add a blue tang?
I am purchasing a saltwater tank of 75 gallons, with the following fish in it already...clown fish, yellow tang, 6 line wrasse, blue chromis, polka-dot cardinal, and 2 antheas (1 male, 1 female) ...I am purchasing this tank from someone else.
Details of Tank! :
75 gallon reef ready Oceanic Aquarium (48"L x 18"D x 21"H)
-Oceanic Cherry stand and canopy
-Sump tank - containing bio balls, protein skimmer, and pump
-All necessary plumbing
-Aqua Medic high intensity pendant light with ballast
-About 75lbs of live rock
-about 100 lbs of live sand
-Corals
-7 fish including: clown fish, yellow tang, 6 line wrasse, blue chromis, polka-dot cardinal, and 2 antheas (1 male, 1 female)
-Coral banded shrimp, and a handful of nassarius snails who burrow in the sand and come out during feeding
A yellow tang and a hippo tang both really should be in a 6 ft tank.
Given that you already have a yellow. I really doubt this will work out .
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