Pangasius hypophthalmus
The Iridescent Shark Pangasianodon hypophthalmus (previously Pangasius hypophthalmus) is a very active catfish. They are schooling fish, and a group of these swimmers makes a delightful display. The name is derived from its juvenile coloring, a silvery iridescence with a couple dark stripes, and a body shape resembling that of a shark. As they reach their adult size, which can be up to a whooping 4 feet (130 cm) in length in the wild, their coloring becomes a uniform darker gray, often without the striping.
The Iridescent Shark Catfish has a very long history with humans. Southeast Asian nations have been utilizing it as an important food fish for hundreds of years and it is also a popular aquarium fish. It is known by a number of common names. The names Pangasius Catfish and Sutchi Catfish are derived from scientific names it had previously been described by, most recently Pangasius hypophthalmus and early as Pangasius sutchi. Tiger Shark, Shark Catfish, and Striped Catfish relate to its appearance, while Siamese Shark and Asian Shark Catfish relate to its place of origin as well as its appearance. Striped Catfish is also its common name in the food fish market.
The Pangasius Catfish are so attractive as juveniles that aquarists find then very desirable. Unfortunately this is a catfish for a very large aquarium only. They are relatively hardy and are peaceful with other fish, as long as their tank mates are too big to swallow. But due to their size they are not the best aquatic fish to keep in a home aquarium. Juveniles can be started in a 100 gallon aquarium, but once they reach their adult size, generally about about 39 inches (100 cm) in the captivity, they will require an aquarium the size of at least 300 gallons or more. They are also very active fish that need a lot of room to swim, and they don’t thrive as well if kept singly as juveniles. Iridescent Sharks really need to be kept in small groups of about 5 or so fish to do well.
The Iridescent Shark is known as a Naked Catfish and like all catfish species it is scaleless, but unlike others its skin is not covered by bony plates or other armor. Consequently it can be easily scratched and damaged. It also does not possess the bottom dwelling habit we usually identify with most catfishes, but rather occupies the middle of the aquarium. They are constantly on the move and will occasionally go to the surface for air. These fish are also diurnal, meaning they are active during the day and enjoy a well lighted aquarium.
Be cautious! The Pangasius Catfish have bad eyesight and they are a nervous fish that can be easily spooked. Don’t tap on the glass or startle the fish as it is likely to injure itself in its mindless flight. They can get hysterical when frightened and dash madly around the aquarium. They will often bash into the sides of the aquarium, ornaments or other fish. After such a flight, you may see the fish sink to the bottom of the aquarium and lie on its side or back until it recovers.