Tangs are also popular aquarium fish for every budget because of their wide variety and physical features. There are over 80 species of Tangs on sale in the market today. The most expensive Tangs (Purple Tangs) cost between $100 and $200. The cheapest i.e. Blue Tangs cost between $30 and $60. It is important to note that expensive Tangs require bigger fish tanks/aquariums i.e. a 100 gallon tank. The cheaper variety of Tangs can do well in smaller tanks i.e. a 50 or 75 gallon fish tank.