Sorry to say your tank sound full, unless you have a large sump like 30gal and 180lbs of LR or and over size canister filter for a 150 gal tank. You have to consider the bio load that is produced by your fish not at present but in the future when they grow. Plus having to many fish in a small tank will cause aggression and then stress and then death. You could always upgrade to a 125 I know your tangs would appreciate it.