The Purple Masked Angelfish (Paracentropyge venustus) is also known as the Venustus or Blue-Backed Angelfish. They require significant room to swim, as well as a good amount of live rock to provide cover and refuge. They are a shy-natured fish that will grow dominant and vibrant in time. Though labeled reef safe, monitor around invertebrates and crustaceans. A healthy variety of crustaceans, meat and algae should be fed regularly. Though a small fish, they require room to swim, and should not be kept in a tank smaller than 75 gallons.