The Iridescent Shark (Pangasius sutchi) is not really a shark, but a type of catfish. They have a grayish, black body with an iridescent stripe running down their sides. They do best when kept in schools of 5 or more, but really grow too large for a home aquarium. In the wild they can grow up to 4 feet long and weigh up to a hundred pounds. In home aquariums, they’re usually not given enough space to grow adequately, and so reach only about 6 - 12 inches long.