Iridescent Shark: Ultimate Guide (Care, Diet, Breeding & More)

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Written By Matt Stevens

Hi, I'm Matt! I've been obsessed with fishkeeping for over 15 years now and created this site to share my knowledge with others.

The Iridescent Shark, sometimes called the Iridescent Catfish, is a large and exciting freshwater fish found in Thailand and Southeast Asia.

In captivity, these fish are more than just ordinary pets. They receive plenty of attention for their appearance, peaceful behavior, and unmatched schooling activities.

But did you know they can grow up to 4ft long in captivity? Or, have you ever wondered why only experienced aquarists with enough resources will want to keep these fish at home?

In this guide, we will help you avoid one of the most common mistakes many aquarists make when choosing an Iridescent Shark for their home aquariums; purchasing a young fish.

We cover everything from pet care to appearance, ideal tank size, tank mates, diet, breeding, and more!

Species Overview

Iridescent Sharks have a few other names, such as Siamese Sharks, Sutchi Catfishes, and Iridescent Catfishes.

Apart from their appearance, these fish have no similarities to the scary saltwater sharks. They belong to the Pangasiidae family with a scientific name, Pangasianodon hypophthalmus.

ColorSilver with a darker dorsal side
LifespanUp to 20 Years
Care LevelAdvanced
Behavior & TemperamentPeaceful
CompatibilityOther large, peaceful fish
Food and DietOmnivores
SizeUp to 48 Inches
Tank SetupPond or large aquarium
Tank Size (Minimum)300 Gallons

If you need an aquarium-friendly freshwater shark to add some much-needed fun to your tank, we can’t think of a more suitable species than the Irridescent Shark.

With their large size, you don’t expect to find them in narrow streams and rivers in their original habitat. Throughout Southeast Asia, they will be swimming freely all over the wide and deep rivers. Specifically, you can find them in Charo Phraya and Mekong, the two most famous large rivers in this region.

Don’t be surprised if you find a meal with Iridescent Sharks in it during a trip to Asia because they’ve been fished, kept, and explicitly grown for food in some regions.


A freshwater Iridescent Shark has an average lifespan of 20 years and above. So, that’s two decades of enjoying their company if you maintain sustainable conditions in captivity.

However, you will shorten these fish’s lifespan if you deprive them of necessities such as food, quality water, and ideal tank mates. 


Just like their name, Iridescent Sharks have a shiny appearance. Even if you’re not fond of freshwater sharks, they are sure to turn a few heads in a home aquarium. They are simply magnificent.

And their captivating look begins with a special dorsal fin resembling a sail, it will either fold or stretch depending on the fish’s activity in the tank.

Young Iridescent Sharks will have darker skin compared to adults. And as they grow, they tend to become less shiny with the subsequent introduction of uniform gray coloration all over their bodies.

Like actual catfishes, these sharks have long barbels to help with navigation through murky waters in the wild. You can’t miss their large eyes that are more pronounced in the juvenile fish.

Like the dorsal fin, their caudal fins have a sail-like appearance with a flappy configuration. On the other hand, the anal fins spread outwards starting from their flat bellies towards the caudal peduncle.

What’s more, a lateral line carrying nervous tissue runs through the fish’s body to help them detect changes in water conditions.

You can differentiate the male sharks from the female species by looking at their sizes. The male Iridescent Shark is usually smaller with a more streamlined body compared to the large, plump females.


Let’s discuss the Albino Shark Catfish variety:

Albino Iridescent Shark

The Albino Iridescent Shark is a major variant of the traditional Iridescent Catfishes that can be identified by red eyes and white coloration all over their bodies.

They resemble the regular fish in many ways and are popular within the fishkeeping community because of their special look.


We mentioned earlier that Iridescent Sharks can get quite large depending on how you care for them at the aquarium. And truly, a typical pangasius catfish will have an average size of 3-4ft in optimum growth.

Unfortunately, the large size only works against them in the fishkeeping community. It is one of the biggest reasons many aquarists are afraid to introduce Iridescent Sharks to home aquariums. Also, it is the only reason beginner-level aquarists may want to avoid these fish altogether.

You may struggle to set up a befitting tank size if you miss the basics. And this is where many aquarists go wrong. Usually, they purchase young fish and are tempted to keep them in small aquariums straightaway, wholly convinced that these are just ordinary freshwater fish.

But after just a few months, it becomes clear that the seemingly small Iridescent Sharks won’t survive in a small tank anymore. At this point, an aquarist’s favorite pastime now looks like an emergency.

If you don’t give up at this point, you may want to switch your fish to a larger tank right away. But it doesn’t have to be that way, especially if you master all the basics from the get-go.

Usually, we encourage aquarists to keep Iridescent Sharks only if they have enough resources or sufficient experience in keeping large fish at home.

Iridescent Shark Care

Iridescent Sharks are fun to watch. They also have precise care requirements, and keeping them at home should be effortless if you master all the care guidelines.

Like we’ve mentioned countless times, the most important aspect to worry about when keeping these fish is their large size. They thrive under the right conditions, which means getting the tank measurements right.

You will have to provide enough swimming space if you want to keep healthy sharks that are comfortable in their new environment.

You could be tempted to keep them in a 40-gallon tank like any other freshwater fish, but we’ve seen how that ends. It’s pretty disappointing in the long run.

We will cover the actual care guidelines in the following paragraphs.

Tank Size

Assuming you are keeping just one Irridescent Shark at home, you will need at least a 300-gallon tank for its health, safety, and comfort. A common trend among many aquarists is to start with smaller tanks before switching the sharks to larger aquariums later on.

Of course, this looks like an excellent strategy, but at what cost? Or, let’s say, sometimes it works. But many times, it doesn’t.

Still, if you opt to tread the same path, be sure to transfer the Iridescent Sharks to a larger tank as soon as they need it. It’s all the more imperative to think ahead and set up the right tank long before your fish approach puberty.

Water Parameters

Iridescent Sharks are an excellent option for many aquariums because of their hardy nature. Even though you will have flexibility in adjusting the water conditions, you should never go below or beyond the recommended standards.

We strongly advise aquarists to keep everything within the ideal standards as you will find out shortly. Maintaining the water parameters at the standard levels can be challenging, but you can always make it easier by measuring the water status regularly using the right aquarium testing kit.

Generally speaking, caring for these fish at home won’t be a problem if you maintain the key water parameters within the following levels:

  • Water temperature: 72°F to 79°F
  • pH levels: 6.5 to 7.5
  • Water hardness: 2 to 20dGH

What to Put in Their Tank?

Regarding tank setup, you will want to mimic or create better conditions than in the fish’s natural habitat. We are talking about Southeast Asia, a region dominated by hot and humid weather and wide rivers. 

For Iridescent Sharks, the primary focus should be on adding the right substrates to encourage security and comfort and providing adequate room for swimming freely in their new environment.

The perfect tank décor will increase comfort and safety. However, excessive decoration risks spoiling the fun and won’t be ideal for your shark friends, even if you regulate the remaining parameters.

We recommend simple decorative elements such as rocks and driftwoods to complete the bottom half of the tank. While it may not be a like for like comparison, this combination mimics the actual riverbeds in the fish’s natural habitat in Southeast Asia.

Also, tranquility is part of the quality care needed by Iridescent Sharks. These fish thrive in a quiet environment with the right tank mates.

Don’t get distracted by their large size. The Iridescent Catfishes are easily startled by excessive noise, which can increase stress levels inside the aquarium.

Now this will surprise you. Unlike most freshwater fish, Iridescent Sharks are not very fond of plants. They like their environment as calm as possible but not necessarily with plenty of vegetation.

Plants may be effective in improving the water quality, but they have no significant benefit in the lives of the Iridescent Catfishes. So, your fish will still be fine if you don’t include natural plants in their habitat.

After all, that’s what they are accustomed to in their natural habitat.

Common Diseases

Ichthyophthirius multifiliis, or Ich disease as it’s commonly known, can occasionally be a problem for Iridescent Sharks, although no more than other freshwater fish.

As you might know, Ich is a common parasitic infection affecting most freshwater fish. With their neat coloration, it should be easier to capture the earliest signs of Ich disease, such as small white spots all over the fish’s body.

Like any other scaleless shark, the Iridescent Catfishes are vulnerable to different skin conditions aside from Ich. While over-the-counter medications may be the easiest solution to managing most of these infections, it’s easier to prevent them by adopting the right strategies from the start.

You can keep these conditions away from your fish community by providing high-quality water, the right diet, and enough swimming space. It’s particularly important to monitor the water status for any slight changes that could expose your fish to severe ailments. 

What Do Iridescent Sharks Eat?

For the Iridescent Shark diet, choosing a variety is always better than restricting them to one meal.

These fish are omnivores who won’t be picky when it comes to feeding in the home aquariums. That gives you more freedom to choose the most suitable food that provides essential nutrients for optimal growth.

As a caring pet owner, you will want to provide the right combination of vitamins and proteins, besides the occasional treats to supplement the fish’s meal.

If you can take an extra step to design a befitting diet plan, you might have just nailed it when it comes to Iridescent Shark feeding.

High-quality flakes are an excellent option to cover most of the nutritional needs of Iridescent Sharks.

Aside from that, you should consider introducing occasional live foods to help with proper nourishment and growth. Some of the best options here include feeder fish, worms, brine shrimp, and bloodworms.

The earlier you understand that most diseases in the freshwater fish community are linked to low-quality food, the easier it will become to manage the sharks’ diet.

And with that in mind, you will want to stick with trusted companies with guaranteed quality on Iridescent Shark food.

Behavior & Temperament

Don’t worry about their “shark” given name. Iridescent Sharks are neither aggressive nor man-eating.

These fish are known for their agility but are easily terrified in home aquariums. For that reason, they are best kept in small communities of at least five species to remain active and secure.

In isolation, loneliness and nervousness will instantly creep in, and Iridescent Catfishes won’t manage to withstand the increasing stress levels for a long time.

Regarding their temperament in captivity, Iridescent Sharks are peaceful fish and will be calm inside the tank most of the time. They rarely display their aggressive side unless they feel threatened inside the tank.

Even then, it won’t be actual aggression but a normal reaction to fear. They do this by dashing or jumping uncontrollably inside the tank.

Iridescent Shark Tank Mates

Iridescent Shark’s best tank mates should be peaceful species that at least match their size. Introducing smaller fish to the aquarium will be like giving these fish their favorite snack, which they will eat happily.

Also, you should never introduce aggressive fish to the same aquarium because your Iridescent Sharks will never defend their territory. They don’t fit that profile.

On that note, you should avoid even the smallest fish with aggressive personalities. It is just not an ideal combination for Iridescent Catfishes.

On the topic of the most suitable Iridescent Shark tank mates, here’s what you will want to have in the same aquarium:

  • Tinfoil Barbs
  • Black Shark
  • Large Plecos
  • Silver Dollar Fish
  • Oscar Fish
  • Bichir

Before introducing a new tank mate, be sure it’s the right fit for your Iridescent Catfishes. Usually, we encourage aquarists to introduce the new fish cautiously as they monitor their relationship with the sharks over a couple of days or weeks. If you don’t notice an unusual reaction by this point, it’s usually a perfect match.


Iridescent Sharks have everything you could be looking for in a freshwater shark, except breeding. At this point, you may have already guessed that breeding these fish is one of the most challenging tasks you will ever face for obvious reasons.

Firstly, the fish’s unique breeding requirements in the wild can be challenging to replicate in captivity. Even before you get started, you will be quickly discouraged by the fish’s large size. But it doesn’t stop there.

It only gets worse when you think of the special conditions that support the shark’s breeding in the wild. In their natural habitat, Iridescent Sharks seek large water bodies to complete the breeding process, which is impossible to replicate at home.

On top of that, migration is part of these fish’s daily life and an important aspect of the breeding process. They won’t even consider breeding if they don’t migrate to the desired locations. This is pretty much impossible to replicate in a confined setting.

Final Thoughts

Large yet very fascinating fish species. Iridescent Sharks are interesting freshwater fish to have in a home aquarium!

While they won’t be the perfect freshwater fish for every aquarist, Iridescent Sharks are worth it if you have the right tank size and enough resources to manage them at home. They are fun to watch in home aquariums and worth every penny.

Apart from their large size, Iridescent Sharks have manageable care requirements similar to most other freshwater fish. If you are willing to give it a try, we would love to hear your story with these fish at home!