Groupers are a large family of saltwater fish characterized by their stout bodies and over-sized mouths. Although a hardy, colorful and highly fascinating species of fish, groupers should only be kept by dedicated aquarists with ample space to raise them. Various species of grouper vary in length from a few feet to well over 9 feet in length. Although most aquarium varieties only grow to around 12 inches in length, they still require extremely large accommodations. Most aquarium kept species of grouper are incredibly colorful and have complex patterns and markings on their bodies. They come in shades of red, yellow, orange, blue, green, purple, brown, white and black.