Iridescent Shark 101: Your Comprehensive Care Guide

Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: May 15, 2024
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Are you looking to add a touch of elegance to your aquarium? The Iridescent Shark might be just what you need – a fish that displays a captivating luminosity. This article delves into the captivating universe of this extraordinary species, revealing its bewitching appearance, habitat, and care guidelines. Whether you’re seeking advice on suitable tank mates, feeding routines, or building the perfect aquatic environment, our article has got you covered. Get ready to immerse yourself in the resplendent underwater world of the Iridescent Shark.

Article Summary

  • Iridescent sharks are large freshwater fish native to Southeast Asia and belong to the catfish family.
  • They have a shark-like appearance with an iridescent glow on their bodies.
  • Iridescent sharks are social fish and thrive when kept in groups of three or more.

Species Summary

Iridescent sharks, scientifically called Pangasianodon hypophthalmus, are a species of large freshwater fish native to Southeast Asia. Despite their name, iridescent sharks are not true sharks but actually belong to the catfish family.

These unique creatures have a distinctive silver coloration and can grow up to 4 feet in length, making them an impressive addition to any aquarium.

Giant Catfish Relatives

One interesting fact about iridescent sharks is that they are closely related to the Mekong giant catfish. Both species belong to the Pangasiidae family and share a common lineage.

Iridescent sharks are sometimes referred to as Siamese shark or sutchi catfish. Both are giant freshwater fish species that can grow to impressive lengths and weights.

The Mekong giant catfish and the Iridescent shark are primarily carnivorous, feeding on smaller fish, crustaceans, and other aquatic organisms. They are opportunistic predators, using their size and agility to capture their prey. While they share commonalities, there are key differences between these related fish species.

Despite these commonalities, there are several key differences between the Mekong giant catfish and the Iridescent shark. One major difference is their physical appearance.

The Mekong giant catfish has a broad and flat head with a large mouth and a smooth and scaleless body. On the other hand, the Iridescent shark has a slender head and a small mouth, a streamlined body, and a distinctive sheen on its scales.

Another difference lies in their habitat preferences. The Mekong giant catfish is primarily found in the Mekong River basin, inhabiting deep pools and slow-moving sections of the river.

On the other hand, the Iridescent shark is commonly found in large rivers and floodplains, as well as reservoirs and lakes. They are known to undertake long-distance migrations, often traveling upstream to spawn.


The Iridescent shark is one of the largest freshwater fish and can grow up to 3 meters in length and weigh over 100 kilograms. As juveniles, they start off as shiny, blue-tinted fish with a sail-shaped dorsal fin. As they grow older, their skin darkens into a solid dark gray coloration.

When light hits their scales at different angles..

They have a streamlined body shape with a silver-gray coloration that shimmers and reflects light, giving them their iridescent appearance. They have an elongated, slender body and a forked tail fin which further enhances their agility and maneuverability.

The head of the Iridescent shark is relatively small compared to its body. It has a pointed snout and large, expressive eyes that are adapted for low-light conditions. These eyes are essential for hunting and navigating their environment.

It has a wide, terminal mouth with numerous small, pointed teeth. This mouth structure is well-suited for their omnivorous diet, which includes small fish, insects, and plant matter.

The scales of the Iridescent shark are relatively large and have a unique iridescent quality. When light hits their scales at different angles, they produce a stunning shimmering effect, hence their name. This adaptation not only adds to their beauty but also provides some camouflage in their natural habitat.

Size, Growth Rate, and Lifespan

In terms of size, iridescent sharks can reach lengths of 3 to 4 feet (approximately 90 to 120 cm) or more. This makes them one of the largest species of catfish in the world.

These catfish are known to be a fast-growing species. In ideal conditions with proper nutrition and care, they can grow at a rapid pace, gaining several inches in length within a year.

On average, they can live for around 20 to 25 years in captivity, but there have been reports of individuals living up to 30 years or more.

Natural Habitat and Migratory Behavior

The iridescent shark catfish, also known as the sutchi catfish, is a freshwater fish species that is native to Southeast Asia. It is commonly found in large rivers and freshwater lakes in countries such as Thailand, Vietnam, and Cambodia.


When water levels rise during the rainy season, they move upstream to areas that were previously inaccessible, allowing them to access new feeding grounds and take advantage of the increased availability of prey. Moving upstream also helps them escape from predators that may be more abundant in downstream areas.

When water levels decrease during the dry season, the iridescent catfish move downstream in search of deeper and more stable water. This migration helps them to avoid being stranded in shallow areas and ensures their survival during periods of low water availability.

The iridescent shark is known to exhibit both upstream and downstream migratory behavior, often associated with the seasonal changes in water levels and the availability of food sources. They are migratory fish that move upstream during the rainy season to spawn and downstream to rear their fry.

This behavior is believed to be influenced by a combination of factors, including the availability of food, water temperature, and the need to reproduce. By moving between upstream and downstream areas, these fish are able to exploit different ecological niches and optimize their chances of survival in dynamic freshwater environments.

Tank and Habitat Requirements

Iridescent sharks, or scientifically referred to as Pangasius hypopthalamus, are popular due to their unique appearance and manageable size compared to true shark species. However, it’s important to note that these fish require specific conditions to thrive. They need a spacious tank with plenty of swimming room and a quiet area where they can retreat.

.. they require a large tank to thrive..

Providing the right tank and habitat conditions is crucial for their well-being. These magnificent creatures require a large tank size for these massive fish to thrive, ensuring they have ample space to swim and explore.

A minimum tank size of 300 gallons (1136 liters) is recommended for just one fish, but if you’re considering keeping massive fish or a school of these graceful swimmers, you’ll need an even larger tank.

To create a suitable habitat for your iridescent sharks, it’s important to incorporate various hiding spots within the tank. Rocks, caves, or driftwood can be used to provide shelter and security for these shy creatures. By offering hiding places, you’ll help them feel more comfortable in their environment.

Maintaining proper water conditions is essential for the health and longevity of your iridescent sharks. These fish thrive in temperatures ranging from 75°F to 82°F (24°C to 28°C).


It’s important to monitor the water temperature regularly using a reliable thermometer and make adjustments as needed. Keeping the water within this optimal range will ensure that your iridescent sharks remain healthy and active.

In addition to temperature control, monitoring other water parameters is equally important. Testing pH levels between 6.5 and 7.5 is crucial since maintaining suitable acidity or alkalinity ensures their overall well-being. Aim for a pH level within this range by using appropriate buffers or additives if necessary.

Water hardness is another factor that needs attention when creating an ideal habitat for iridescent sharks. The recommended range falls between 2.0 and 29.0 dgH (degrees general hardness). Monitoring water hardness regularly will help you maintain optimal conditions.

To keep your iridescent sharks happy and healthy, it’s vital to ensure high-quality water at all times. Regularly check water levels such as ammonia, nitrate, nitrite levels using test kits and promptly address any issues that arise. Maintaining a clean and well-filtered tank is crucial for their overall health.

Iridescent sharks are social by nature..

Tankmates and Temperament

Iridescent sharks, or Siamese shark catfish, are social by nature and thrive when kept in groups of three or more. Their peaceful temperament makes them excellent additions to community tanks, but it’s essential to select suitable companions to ensure a harmonious environment.

Given their schooling nature, iridescent sharks feel most comfortable when surrounded by other members of their kind. This helps to mimic their natural behavior and provides them with a sense of security in the tank. When they are kept alone or in small groups, they may become stressed and exhibit unhealthy behaviors.

Iridescent Shark Tank Mates

One key aspect of housing iridescent sharks with other fish is monitoring their behavior closely. While they generally get along well with compatible tankmates of similar size, caution is needed when dealing with aggressive species.

Some overly active fish can startle iridescent sharks and make them skittish. Therefore, it’s vital for fish owners to observe how the different species interact and make adjustments if necessary.

Here are a few more examples:


These fish are known for their peaceful temperament and beautiful colors. They can coexist with iridescent sharks as long as they are of similar size. Gouramis also prefer slow-moving water, which is ideal for the iridescent shark’s needs.

Silver dollars

These silver dollar fish have a similar size and temperament to iridescent sharks, making them compatible tank mates. They are known for their silver color and round shape, adding visual interest to the aquarium. Silver dollars are also peaceful and won’t cause any harm or stress to the iridescent shark.


These vibrant and active fish can coexist with iridescent sharks as long as they have enough space to swim. Rainbowfish are known for their peaceful fish nature and can add a splash of color to the aquarium. They are also similar in size to iridescent sharks, reducing the risk of aggression.

Bala sharks

These fish are closely related to iridescent sharks and make excellent tank mates. They have a similar appearance and temperament, creating a harmonious environment in the aquarium. Bala sharks are peaceful and won’t cause any harm or stress to the iridescent shark.

Clown loaches

These playful and social fish can coexist with iridescent sharks as long as there is enough hiding space in the tank. Clown loaches are known for their vibrant colors and unique patterns, making them a visually appealing addition to the aquarium. They are also peaceful and won’t pose a threat to the iridescent shark.


These sensitive fish prefer the company of peaceful community fish that won’t pose a threat. Good options include tetras, barbs, or larger cichlids known for their calm demeanor. It’s important to choose iridescent shark tank mates carefully, ensuring they are not easily irritated or prone to aggression.

Hardy Freshwater Fish

In addition to being compatible with peaceful fish species, iridescent sharks, scientifically referred as Pangasianodon hypophthalmus, make good tank mates due to their hardy nature. They can adapt well to various water conditions and tolerate slight fluctuations in temperature and pH levels.

This resilience makes them suitable companions for other freshwater fish that share similar environmental requirements.

Monitor for Stress and Aggression

It is important to avoid keeping these iridescent fish with aggressive or territorial species. These types of fish can harm or stress the sharks, leading to potential injuries or even death.

They may become skittish if housed with overly active fish that constantly swim around or chase them. This can cause stress and anxiety for the sharks, affecting their overall health and well-being.

Iridescent sharks can be kept with compatible tankmates of similar size. However, caution is needed when introducing aggressive species to the tank. Aggressive fish may pose a threat to the iridescent sharks, especially if they are smaller in size.

Some specific examples of fish species that are not compatible with the iridescent shark include aggressive and territorial species such as cichlids, bettas, and tiger barbs.


It is crucial to research the temperament and compatibility of schooling fish with potential tankmates before adding them to the tank. This will help ensure a harmonious and stress-free environment for all the fish in the aquarium.


Cichlids, known for their aggressive nature, can become highly territorial and may attack the iridescent catfish. Their aggressive behavior can lead to stress and potential injuries for the catfish.


Bettas, also known as Siamese fighting fish, are highly territorial and can be extremely aggressive towards other fish, including the iridescent shark. The bettas may perceive the catfish as a threat and may exhibit aggressive behavior, resulting in harm to both species.

Tiger Barbs

Tiger barbs are notorious for their nipping behavior, especially in groups. They have a tendency to nip at the fins of other fish, including the iridescent shark catfish. The constant harassment and stress caused by the tiger barbs can lead to health issues for the catfish.

Iridescent Shark Care

Caring for iridescent shark requires attention to detail and a commitment to maintaining optimal tank conditions. These beautiful creatures, also known as pangasianodon hypophthalmus or iridescent catfish, are popular among aquarium enthusiasts. To ensure their well-being, it is crucial to follow proper Iridescent Shark care guidelines.

Iridescent sharks produce a significant amount of waste..

Regular Water Changes

Performing regular water changes is essential for maintaining the water quality in the tank of your iridescent shark. Aim for at least a 25% water change every two weeks. This practice helps remove accumulated waste and toxins that can harm the fish.

By keeping the water clean and well-maintained, you provide a healthy environment for your iridescent shark to thrive.

Powerful Filtration System

Iridescent sharks, also known as the Siamese shark catfish or scientifically referred to as Pangasianodon hypophthalmus, produce a significant amount of waste due to their size and feeding habits. To effectively handle this high waste production, it is crucial to invest in a powerful filtration system. A robust filter will help remove excess debris and maintain excellent water quality.

Consider using a high quality canister filter or an external filtration system to ensure efficient cleaning.

Proper Lighting Schedule

Creating an appropriate lighting schedule is vital for the well-being of your iridescent shark. During the day, make sure the tank receives ample light as these fish enjoy swimming in bright environments. However, during nighttime hours, provide dim lighting or use moonlight LEDs to simulate natural conditions and allow them time to rest.

Keep an eye out for signs of disease..

Monitoring Health

Regularly monitoring your iridescent shark’s health is essential for early detection of any issues they may face. Keep an eye out for signs of disease such as loss of appetite, abnormal swimming patterns, or visible parasites on their bodies.

Keeping iridescent sharks mean that these fish are susceptible to stress-related health problems like skin conditions including ich (white spot disease). Prompt action can significantly increase their chances of recovery.

Avoid Stressful Conditions

To keep your iridescent sharks in optimal health, it is crucial to minimize stress factors. These fish are particularly sensitive to stress-related issues, which can lead to various health problems.

Avoid keeping them alone or in a tank that is too small for their size. Providing adequate space and suitable tank mates can help reduce stress levels.

Food and Diet

Feeding your iridescent shark a proper diet is crucial for its overall health and well-being. These fascinating creatures are omnivores, meaning they consume both plant-based and meat-based foods. By offering them a varied diet consisting of high-quality pellets, frozen foods, and occasional live or frozen insects or small crustaceans, you can ensure they receive the necessary nutrients for their growth and vitality.


It’s important to note that while these fish have very poor eyesight, they possess other sensory abilities that compensate for this limitation. In the wild, iridescent sharks inhabit rivers with murky waters such as the Chao Phraya River in Thailand or the Khone Falls in Laos.

It is recommended to feed your iridescent shark once or twice daily. However, make sure to provide an amount that they can consume within five minutes. Overfeeding should be avoided as it can lead to various health issues for the fish and result in poor water quality within their habitat.

To supplement their diet with essential nutrients, including vegetable matter such as blanched spinach or peas is a good idea. This provides additional fiber and vitamins needed for their well-being.

Alongside these plant-based options, you can also feed them a flake-based diet that contains protein-rich ingredients suitable for omnivorous species like the iridescent shark.

Occasionally incorporating live foods into their diet is beneficial as well. Bloodworms and brine shrimp are popular choices among fishkeepers due to their high protein content. These live foods mimic what iridescent sharks would consume in their natural environment.

Breeding can be quite challenging..

Providing appropriate food not only ensures the nutritional needs of your iridescent shark are met but also helps prevent common diseases associated with poor diets. By maintaining a balanced diet rich in protein sources from both plants and meat, you contribute to their overall health and vitality. Remember to create a feeding routine that suits the needs of your fish while considering their natural environment and dietary requirements.

Breeding Iridescent Sharks

Breeding iridescent sharks in captivity can be quite challenging due to their migratory nature and specific requirements. While it is nearly impossible to breed them in a home aquarium, experienced breeders with large tanks and specialized techniques to breed iridescent sharks have had some success.

Specific water conditions are necessary to trigger breeding behavior in iridescent sharks. Spawning usually occurs during the rainy season when water levels rise in their natural habitat. To simulate this environment, breeders must carefully monitor and adjust the water quality and temperature in their tanks.

How to Breed Iridescent Sharks?

Successful breeding often requires hormone injections or other specialized techniques by experienced breeders. These methods help stimulate the reproductive systems of the fish and increase the chances of successful spawning.

It’s important to note that these techniques should only be performed by professionals who have extensive knowledge and experience with iridescent shark breeding.

While it may not be feasible for most hobbyists to breed iridescent sharks at home, these magnificent migratory fish continue to captivate enthusiasts around the world. Their unique behaviors and striking appearance make them a popular choice for large public aquariums that have the resources to accommodate their needs.


One of the main reasons breeding iridescent sharks is difficult is because of their migratory behavior. These fish are known for their long-distance migrations, which makes it hard to replicate their natural breeding conditions in captivity. They require large tanks that mimic the spaciousness they need for migration.

Caring for the Fry

In terms of care, juvenile iridescent sharks require a well-maintained tank with proper filtration systems. They should be fed a balanced diet consisting of live or frozen foods such as brine shrimp and other small aquatic organisms.

Providing ample hiding spots with plants and decorations can also help create a suitable environment for growth.

Regular monitoring of water parameters is crucial. Iridescent sharks are susceptible to various diseases, so maintaining good water quality is essential for their overall health and well-being. Quarantining new fish before introducing them into an existing school can also help prevent potential infections from spreading.

Frequently Asked Questions

Are iridescent sharks aggressive?

No, iridescent sharks are not generally aggressive. They are known to be peaceful and docile fish, making them suitable for community aquariums.

However, it’s important to note that as iridescent sharks grow, they may become more active and require more swimming space. Monitoring tank dynamics and providing suitable tank mates are crucial to maintaining a harmonious environment.

How big does an iridescent shark get?

Iridescent sharks can grow quite large, reaching impressive sizes in the right conditions. On average, they can grow up to 3 to 4 feet (90 to 120 centimeters) in length.

However, it’s essential to note that their growth is highly dependent on various factors such as tank size, water quality, and diet. Providing a spacious aquarium and meeting their care requirements will allow them to reach their maximum potential size.

Which fish can be kept with iridescent sharks?

Iridescent sharks are compatible with a variety of peaceful and similarly-sized fish species. Good tank mates can include other large freshwater species like Silver Dollars, Tinfoil Barbs, and Giant Gouramis.

It’s important to avoid small fish that may be seen as potential prey by the iridescent shark. Observing compatibility, considering behavior, and providing ample swimming space are key factors in selecting suitable tank mates.

Are iridescent sharks good pets?

Iridescent sharks can make good pets for experienced aquarium keepers who can provide the appropriate care. They are fascinating to observe due to their unique appearance and graceful swimming style.

However, it’s important to note that iridescent sharks require large aquariums, proper filtration, and a balanced diet. They also grow quite large, so prospective owners should ensure they have the space and resources to accommodate these impressive fish.

Why are they called iridescent sharks?

Iridescent sharks are named for their stunning iridescent appearance. Their scales possess a reflective quality that gives them a shimmering, almost metallic look when light hits them at different angles.

This iridescence is due to the structural properties of their scales, which reflect and refract light, creating a captivating visual effect. The name “iridescent shark” is a nod to this shimmering and radiant characteristic that distinguishes them from other fish species.

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