It is not a small tank. 46 gal is big! you mean small for the fish? i supposed... :)
Swing, tangs can get aggressive if cramped for space. As some tangs reach 25-35 cm, 46 gallons may not be enough to accommodate even 2 large tangs.:) 90 gallons will often be the option for 2-3 large tangs. Some may coexist but others will not.