The iridescent shark, also known as the Pangasius catfish, is a large tropical species native to Asia. These fish often reach an adult size of up to 4 feet (1.2 meters), and may therefore not be suitable pets for most hobbyists. They typically require a very large tank, ranging in size from a minimum of 300 gallons (1,336 liters) to 2,000 gallons (7,751 liters). They usually feed on smaller fish, and can live for up to 20 years.
These fish can grow quite large, so they can be difficult for many hobbyists to keep. The iridescent shark typically requires a very, very large tank, since they are usually quite active. A tank size of 300 gallons (1,336 liters) is considered minimal for these fish. They are, nevertheless, generally affordable and easy to acquire, and they are usually bred on fish farms.
The females of this species are generally wider in body than the males. Both males and females may have stripes, the males generally have darker stripes.
Though often referred to as a catfish, the iridescent shark is not usually a bottom-feeding fish. It typically prefers to occupy the mid-range waters of its habitat, whether in a tank or in the wild. These fish will usually feed on whatever small fish are provided them. A varied diet of fish flakes, pellets, and live or frozen blood worms, shrimp, and feeder fish is generally recommended. The iridescent shark isn't usually aggressive and can, in theory, be kept in an aquarium with other tank mates. This fish's sheer size, however, often precludes keeping it in an aquarium environment with other fish.
The Pangasius catfish is known as an easily startled breed. When frightened, these fish may fly into a panic and injure themselves against the side of the tank or against decorations inside the tank. They may also present a danger to other fish in the tank when panicking.
People wishing to keep this fish in an aquarium environment are generally advised to avoid starting the fish, and to offer it shelter in the form of aquatic plants. Young specimens normally form schools in the wild, so an immature iridescent shark may find comfort in the presence of others of its species. As they grow into adults, however, these fish generally begin to prefer more solitude.
The typical iridescent shark is an albino with very poor vision. They can be sensitive to light, and generally prefer a dimmed environment. Some enthusiasts believe these fish are calmer when kept in a dim environment.