Iridescent Shark Stats InfographicThe Iridescent shark, scientifically called Pangasius hypopthalamus, is a shark catfish species native to Southeast Asia.

But don’t get too scared by its name. It is, in fact, not a shark but simply a catfish. It is also known as iridescent catfish or sutchi catfish. Sauvage was the first one to define this species in 1878.


Scientific name Pangasianodon hypophthalmus
Other names Iridescent catfish, Siamese shark, sutchi catfish
Temperature 72 F 79 F (22 C-26 C)
pH 6.5 7.5
Hardness 2.0 29.0 dgH
Temperament Peaceful
Size 3ft 4ft

Iridescent Shark Overview

Iridescent Shark got its name for the glow or iridescence that can be seen on the bodies of juveniles. They are freshwater sharks because they have a shark-like appearance similar to other shark catfish species. However, their meat is usually marketed under the name swai in many countries. They are also known as Siamese sharks.


Iridescent shark breedingThe natural habitat of the iridescent shark is the Mekong basin and the Chao Phraya river, where it is also cultivated in large amounts for food. It can also be found south of the Khone Falls.

However, thanks to the popularity of these fish in the aquaculture sector, they have also been introduced in many other rivers and tributaries. In 2015 a group of environmentalists also found these fish in the tributaries of Magdalena River, where it is assumed to have reached because of the illegal fisheries in the area.

These fish are all migratory. In most regions, they move upstream to spawn during the flood season when the waters are high. Then when the water levels recede again, they return downstream to create their rearing habitat. These migrations occur at different periods based on the region.

While upstream migration is between May to July in the Mekong river basin and the downstream migration between September and December, it happens between October and February in the Khone Falls, peaking around November to December. The receding waters at the end of the flooding season are the main trigger behind these migrations.


It has been mentioned quite often by now that iridescent sharks can grow quite large. If you give them enough room to grow and feed them properly, a full-grown iridescent shark can reach more than three feet in length, which is around one meter. For an average iridescent shark, the size for adults can reach from three to four feet in length, which means they can grow up to almost 50 inches!

However, you shouldn’t expect to see such drastic growth in your home aquarium. Even if you give them a huge tank, it will still not have the same space as a river. So the lack of space might cause a significant stunt to their growth. As a result, most iridescent sharks kept at home in a standard-sized tank only grow up to 6 to 12 inches.

But if you can provide them a huge tank, they might grow much bigger than that but not attain that whopping length of four feet. Even without reaching their maximum height, they might become a serious problem for fish owners who don’t have all the required knowledge about them.

You have to understand their maximum size and growth rate properly before deciding if it’s possible for you to buy them. Otherwise, your fish will just lead a life of suffering until you have to give it away eventually.

So make sure you are prepared to house a fish of this size before deciding if you want it or not. Don’t simply run after it because it’s pretty. From the moment you own the fish, enduring its maximum comfort is your number one responsibility.


Iridescent shark careThe average lifespan of an iridescent shark is much longer than a regular fish. It can go on the upward of twenty years, during which they will obviously grow quite huge.

If you provide them with the right environment and adequate foods, they should be able to live to their teens, at least if they don’t get attacked by any diseases.

Remember that inadequate space in the aquarium can reduce the lifespan of your iridescent shark by a lot of years, alongside stunting their growth. If you can’t recreate the environment of the river inside the tank, or if you keep them with other fish they don’t get along with, or if there is too much movement and noise around the tank—all of it can lead to increased stress levels which will reduce their lifespan.

Growth Rate

Most iridescent sharks will be around two to four inches when you buy them. Their growth rate is actually very fast compared to most other fish, especially if you give them a huge tank and a meaty diet filled with protein. In that case, you will see them reach around a foot of length within a year. A similar rate will continue in the years to come.

Body and Coloration

Iridescent sharks are one of the most beautiful freshwater fishes out there, which is why they are so high in demand, even among people who are not ready to raise them. Their shiny, iridescent color gives them a dazzling appearance which is absent in other catfishes.

However, that only lasts for the juveniles. After maturing, the adults adopt a uniformly gray body color. Juveniles will have a black stripe along the lateral line of their body and a second black stripe below it. The fins will be dark gray or black for both juveniles and adults.

One feature that you will immediately notice in your iridescent shark is its unique dorsal fin shaped like a sail. It will fan out or tuck back in depending on how the fish is swimming in the tank. Like other catfishes, iridescent sharks also have long barbels. They use these barbels to navigate in waters where they can’t see too well.

You will also notice that they have rather large eyes compared to most other fish, especially highlighted when they are younger. But they grow into them as they age and become a larger size overall. Just like their dorsal fin, their caudal fin is also somewhat flappy, made of sail-like tissues. As for their anal fins extend from the flat part of their belly to the bottom of their caudal peduncle.

If iridescent sharks aren’t beautiful already, you will be utterly stunned by their albino family! That’s right. You can find albino iridescent sharks from various sellers. Since they are also quite high in demand but are rather rare still, they might be super expensive to buy, and you might not even find them in many parts of the world.

Regardless, you will be absolutely charmed by their sharp and shiny white body, which will stand out for sure in your aquarium. Other than that, they are built exactly like a regular iridescent shark. The only other difference you will find is that they have red eyes.

Iridescent Shark Care

Iridescent sharks are known to be fairly difficult to take care of. Even for a single one of them, you will need a huge tank as they are active fish that require a lot of space. On top of that, since they are schooling fishes that prefer groups for being accustomed to living in rivers, you might have to buy a bunch of them at once and put them in a much bigger tank. The overall costs will be a lot too.

You will also have to be careful not to conduct any hasty movements around the tank they live in. Because of their poor eyesight, they easily get scared by any detected movement outside their habitat and see it as a threat.

They become stressed, and their first instinct in such a case is to flee. But when they do so in the limited space of the aquarium, they might bump into the glass and injure themselves or injure other fish in the tank.

The care requirements themselves aren’t too much. But you will need quite a lot of space in your aquarium for them to live happily and healthily, and you will need to spend a lot of money behind them. It might be a bit difficult for first-time fish owners to handle this fish, but it’s not impossible. It’s just not worth the trouble if you can’t give it everything it needs.

That aside, the care itself is quite manageable if you already have a certain level of experience as a fish owner. There isn’t any additional hassle you have to go through regarding the water parameters, the food, and the tank mates.


Your iridescent shark’s diet should not be too much of a headache, as they are omnivores, so they will eat all types of foods. So it’s your job to find the right kind of foods for your fish to ensure their best health. Like most other fish, you can give them a flake-based diet. Make sure the flakes are high quality and from a good company.

Flakes are the best because they usually cover all their basic food needs, fight off potential diseases, and promote growth. But giving them only that can get monotonous. For the best results, throw in some live food once in a while. These can include bloodworms, brine shrimps, feeder fish, and such. Live foods will give them the additional protein they need to stay healthy and grow fast!

Setting Tank For Iridescent Shark

Iridescent shark babyOne of the biggest mistakes fish owners make with the iridescent shark is getting a small tank. When they are juveniles, you might think that a 40-gallon tank should be more than enough for them.

But their growth rate is often underestimated. Iridescent sharks can actually grow quite large and also need a lot of space to move around as they have an active personality.

But you should always get a tank thinking of the future, as in, the maximum size of the fish. For a fully grown iridescent shark, you need at least a 300-gallon tank. With that, they will have enough room to swim freely and won’t feel cramped. Of course, you can keep them in a smaller tank for now and move them to a bigger one once they grow bigger.

But remember to do this transition before they need it instead of after. By the time you realize that your shark is feeling suffocated in a small tank, you might already be a few months late. Then it will take you more time to buy a new tank and arrange it properly. So your iridescent shark will feel uncomfortable for a long time, which can negatively impact its lifespan.

That being said, the water parameters for iridescent sharks are nothing hard to maintain and give you a fairly flexible range. Keep the temperature between 72 F to 79 F and the pH level between 6.5 to 7.5. The water hardness should be between two to 20 dGH. In larger tanks, it might take a while for you to align these levels, which is another reason you need some level of experience to raise an iridescent shark.

To make your iridescent shark feel at home, you should try to incorporate the river’s environment inside your tank to the best of your abilities. Their natural habitat is in the deep waters of southeast Asia. So you want to make sure that the bottom of the tank is filled. You can put driftwood and decent-sized rocks, which the river beds usually cover, within their real homes.

However, when you’re filling up the tank with such things, make sure to leave just enough to let them have a lot of space to swim over. Don’t fill it too much, as the fish is very large and it can feel congested. Moreover, keep the tank in a quiet spot of the house, as they can get easily startled with the smallest noises and movements.

Iridescent Shark Tank Mates

Though the name suggests them to be maneaters, iridescent shark behavior is actually one of the most aquarium-friendly ones out there. They have a calm and peaceful temperament and won’t cause any trouble with other fish or show any kind of aggression. However, you will notice differences in their behaviors depending on whether they are alone or in a group.

As mentioned earlier, these are schooling fish, so they perform much better in groups. They get lonely and scared easily, so they will always show signs of nervousness and stress if you keep them alone in the tank. But if you keep them in a group alongside fellow iridescent sharks, they will feel safer and calmer, and you will also see them being more active. That’s why it’s not recommended you get only one iridescent shark for your tank.

However, iridescent sharks are rather jumpy and always stay on edge, so they get spooked easily. When scared, they will dart and splash around quite a lot, which will cause a lot of movement as well. But that is not a sign of aggression in any way. Regardless, you should avoid putting fish that are easily irritated by this kind of movement in the same tank as the iridescent sharks.

That aside, you shouldn’t choose small tank mates for these fish too, or they might be mistaken for food, and your shark might eat them. Choose fish of similar size as the tank mate. Aggressive fish might choose an iridescent shark as their target as the latter doesn’t really fight back, which can lead to injury and such. So that should also be avoided.

Some worthy candidates for being your iridescent shark’s friends are bichir, silver dollar fish, large plecos, Oscar fish, black shark, tinfoil barbs, and such. Others are fine, too, as long as they fit the guidelines and the water parameter. You should always monitor how the fish get along in the first few weeks after you put them together.


The hardest part of being an owner of iridescent sharks is to breed them. In fact, it is more or less impossible even if you are highly ambitious, confident, and knowledgeable. They need very specific parameters to breed, and this type of parameter can only be found in nature. Replicating it is near impossible.

But you wouldn’t have to go that far. Iridescent sharks need a huge amount of space to breed, which is simply impossible to provide in a home aquarium. This is because, in their natural habitat, they seek out massive bodies of water before breeding. Even if you have an entire wall of your room dedicated to the aquarium, it will still not be enough.

And that’s not all. It was previously mentioned that they are migratory fishes, so they need to go through the process of moving upstream and returning downstream to understand they are ready for breeding. If they don’t migrate, it won’t click in their brain that they might be able to breed even without doing it. And this migration is impossible to replicate in a home tank.


Now you have all the information you need about iridescent sharks and how to raise them. Let’s take a second look at the most important points you should keep in mind:

  • Iridescent sharks are a species of catfishes native to Southeast Asia.
  • Iridescent sharks are migratory fish, and their breeding season depends entirely on migration.
  • These fish need at least a 300-gallon tank to live comfortably, and it needs to be even bigger for a group.
  • They are schooling fish who will do better in groups than alone.
  • They are very sensitive to noise and movement, so the tank should be placed somewhere quiet.
  • It is not possible to breed them in a home aquarium.
  • Give them adequate space and enough meaty diet to ensure they live long and grow large.

Iridescent shark fishIridescent sharks are so gorgeous that many people would love to own them. But not everyone has the capability to do so. If you are confident that you are ready to be the parent of an iridescent shark, then make sure to take all the required preparations before adding them to your tank!

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