Iridescent Shark Catfish are very graceful, elegant swimmers and beautiful fish to watch!

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 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.

Scientific Classification


Iridescent Shark – Quick Aquarium Care

Aquarist Experience Level:Advanced
Aquarium Hardiness:Moderately Difficult
Minimum Tank Size:100 gal (379 L)
Size of fish – inches51.2 inches (130.00 cm)
Temperature:72.0 to 79.0° F (22.2 to 26.1&deg C)

Habitat: Distribution / Background

The Iridescent Shark Pangasianodon hypophthalmus was described by Sauvage in 1878. However due to the fact that Southeast Asian nations have been catching this fish as a food source for hundreds of years, no one is sure who discovered it. This species has recentlybeen moved from the Pangasius genus to the Pangasianodon genus. Pangasius hypophthalmus is now a synonym rather than a valid species name, as is the even early described name Pangasius sutchi.

The Iridescent Shark is native to the Mekong basin, as well as the Chao Phraya River and Maeklong basin, chiefly in Thailand, Myanmar, Laos, and Vietnam. They have also been Introduced into other river basins for aquacultural purposes. They are found as juveniles in schools of large numbers, especially in stretches of rapids in major Asian rivers, but are loners as adults. In the wild they feed on fish, shrimp and various crustaceans, insect larvae, fruit, and vegetable matter.

They are commonly available in the aquarium trade and are a food stable in Southeast Asian countries such as Thailand, or Laos, where it is used as an important food source. In Thailand, it is considered the most important aquaculture fish. Other common names they are known by are Pangasius Catfish, Sutchi Catfish, Siamese Shark, Asian Shark Catfish, Shark Catfish, Tiger Shark, and Striped Catfish.

There are several variations of this fish. Most notably are the Albino Iridescent Shark or Albino Pangasias Catfish which is commonly available, and also ‘short body/balloon’ forms. The latter form remains smaller than the natural fish. The Iridescent Shark Catfish is on the IUCN Red List for Least Concerned with a stable population.

  • Scientific Name: Pangasianodon hypophthalmus
  • Social Grouping: Groups – They are found in large schools as juveniles, but but are loners as adults.
  • IUCN Red List: LC – Least Concern


The Iridescent Shark a large sized catfish with a body shape resembling that of a marine shark. It has a laterally compressed body, and like other catfish it has two pairs of barbels. It has a short dorsal fin on top with one or two spines and also has strong spines on each of the pectoral fins. It has a well developed adipose fin on the underside and a long anal fin (tail fin).

This catfish typically has a glow or iridescence exhibited in juveniles, along with two dark broad vertical bands. One is along the lateral line and the other is just below it, extending from above the pectoral fin base towards the forepart of the anal fin. Adults are generally darker colored and often lack the striping, yet they still retain the glimmering glow that gives them their name. The fins are dark gray or black.

This is a large fish that can reach a maximum size of 4 feet (130 cm) in length and have been known to weigh 97 lbs. (44.0 kg). They will generally reach about 39 inches (100 cm) in the aquarium, and have a lifespan of up to 20 years. There are also other species of Pangasius that are sometimes sold as Pangasius Catfish, namely Pangasius pangasius and Pangasius gigas, that can reach 9 feet (300 cm) long!

  • Size of fish – inches: 51.2 inches (130.00 cm) – They usually only obtain about 39 inches (100 cm) in the aquarium.
  • Lifespan: 20 years

Fish Keeping Difficulty

While Pangasius Catfish are considerably hardy, they are not the best aquatic fish to keep in a home aquarium. This is due to the fact that once they reach their adult size they will require an aquarium the size of at least 300 gallons, if not larger. They are peaceful, but only if kept with fish that they cannot swallow. They are unfussy about water chemistry as long as the water is kept clean. and will eat nearly anything.

  • Aquarium Hardiness: Moderately Difficult – Their skin is very delicate and can easily be damaged leaving the fish vulnerable to infection.
  • Aquarist Experience Level: Advanced – Advanced, to expert due to the large size this fish can potentially reach, and the size the aquarium of this fish must have to grow to its full potential.

Foods and Feeding

The Iridescent Shark Catfish is an omnivores species, known to consume generally anything that it can find. As they grow larger, they are known to consume more live and meaty foods. As they get older they loose their teeth, and like the Pacus, become more and more vegetarian.

In the home aquarium they will generally eat all kinds of live, fresh, flake and pellet foods. These fish must have a balanced diet of green and meaty foods. To keep a good balance give them a high quality flake or pellet food two to three times daily, but give them only what they can consume within 5-10 minutes. Also feed brine shrimp (either live or frozen) or blood worms. You can supplement with live foods such as feeder fish, which have been quarantined and fed proper food, to gain excellent nutritional value. Additionally, these fish will accept live crickets, or worms.

  • Diet Type: Omnivore – As it ages, Pagnasius Catfish will become increasingly herbivorous.
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet – As they get older they loose their teeth and become more and more vegetarian.
  • Meaty Food: Half of Diet
  • Feeding Frequency: Several feedings per day – Feed two to three times daily, but give them only what they can consume within 5-10 minutes.

Aquarium Care

The Iridescent Shark Catfish are not too fussy about water chemistry as long as the water is kept clean. However they do prefer a soft acid water, so testing the pH will be helpful. Unless, your aquarium is equipped with an ample filter, change 25% of the water in the aquarium on a weekly basis.

  • Water Changes: Weekly – Water changes of 25% on a weekly basis.

Aquarium Setup

The Iridescent Shark gets very large and requires ample room in order to swim. A minimum 100 gallon aquarium will work whiles a juvenile, a 300 gallon aquarium is recommended for the adult. The aquarium should be setup to resemble the fish’s native environment, which is a typical river, with driftwood and river rocks. As juveniles, these fish may prefer to hide amongst the driftwood. Have a tight fitting lid on the aquarium as these fish are known to jump. Due to their large size, heaters and other aquarium items can be broken. They require a large biological filter because they produce a great deal of waste.

  • Minimum Tank Size: 100 gal (379 L) – This fish grows to over 3 feet and will eventually need a 300 gallon tank or larger.
  • Suitable for Nano Tank: No
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting – These fish are easily stressed. Low lighting will be appreciated by new young fish until they are acclimated and comfortable.
  • Temperature: 72.0 to 79.0° F (22.2 to 26.1&deg C)
  • Range ph: 6.5-7.5
  • Hardness Range: 2 – 20 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: Middle – They will swim in all levels, but generally the middle.

Social Behaviors

When they are young the Pangasius Catfish like to school up, but they will become more and more solitary as the get older. They are generally a good community fish and can be kept with most size tank-mates as long as they are too big for to be swallowed.

  • Venomous: No
  • Temperament: Peaceful – This fish likes to live in a school especially when young, however if given insufficent space as an adult the school life may become tense or the fish may become much more solitary. Finally it should be noted that this fish has poor eyesight and is fairly high strung so the aquarist should be absolutley certain that their specimens never become startled as panicked injury will likely result.
  • Compatible with:
    • Same species – conspecifics: Yes – As juveniles they will not thrive well unless they are kept in a school with about 5 or more of their own kind.
    • Peaceful fish (): Safe – It is not recommended to house this species with small fish since they may become a meal.
    • Semi-Aggressive (): Monitor – Can be kept with Plecostomous and Synodontis Catfish. Caution with Bichirs and Tinfoil Barbs.
    • Aggressive (): Monitor – Larger cichlids may get along with the Pangasius, but it is not guaranteed. Caution with large Jack Dempseys and other large cichlid species such as Midas, or Snooks.
    • Large Semi-Aggressive (): Monitor – Caution with Arowanas and Red Tailed Catfish.
    • Large Aggressive, Predatory (): Threat – Caution with Peacock Bass.
    • Monitor
    • Shrimps, Crabs, Snails: Threat – is aggressive – It is not advisable to keep this fish with invertebrates as they are part of this fish’s natural diet.
    • Plants: Safe

Sexual differences

Females are said to be larger and “stockier” than males and have lighter patterning (striping) than males. Generally, these differences are impossible to detect at a juvenile age, or the age most pet stores offer them for sale.

Breeding / Reproduction

The Iridescent Shark Catfish have not been successfully bred in aquariums due to spawning habits and the massive size of the adults.This is a migratory species that travels upstream to spawn during late spring and summer months. These breeding conditions are mostly impossible to replicate in the home aquarium. They are bred in huge ponds in southeast Asian nations such as Thailand, and Singapore. Juveniles are also harvested from wild populations and raised in floating wooden containers.

  • Ease of Breeding: Unknown – This fish is too large to be bred in the home aquarium although it is propagated in ponds in South East Asia as a food fish.

Fish Diseases

Iridescent Sharks are vulnerable to many common fish diseases such as Ich and fungus related diseases. Like most catfish,being scaleless it makes them difficult to treat if they get Ich. Nearly all ich cures say to use them at half-strength on catfishes and scaleless fishes and this is absolutely a necessity for iridescent sharks. If infected, these fish can more easily be treated with medicines such as melafix, and used as directed.

These easily frightened fish are also prone to getting scratched up from mad dashes around the aquarium. Adding a squirt of a slime coat replacement like NovAqua or Stress Coat can help. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.

Because they are a scaleless fish, catfish can be treated with pimafix or melafix but should not be treated with potassium permanganate or copper based medications. Malachite green or formalin can be used at one half to one fourth the recommended dosage. All medications should be used with caution.


The Iridescent Shark or Pangasius Catfish are readily available in most pet stores and online, and are moderately priced. The Albino Iridescent Shark or Albino Pangasias Catfish which is commonly available, and also the ‘short body/balloon’ form can occasionally be found.

Due to their size and habitat requirements, aquarists will need to be prepared to provide a large aquarium of 300 gallons or more once they reach adult size.



Featured Image Credit: GOLFX, Shutterstock