A tank full of baby iridescent sharks is a beautiful sight. These fast, eager eaters might seem like the perfect addition to your community tank. But there is a lot more to iridescent shark care than you might think.
What is the Iridescent Shark?
The iridescent shark is not a true shark. It’s a freshwater catfish in the family Pangasiidae. Pangasiid catfish include some of the largest freshwater fish in the world, like the Mekong giant catfish (Pangasianodon gigas).
Iridescent sharks don’t grow as big as the Mekong giant catfish (10 feet). But they are still difficult to house as they grow up. And they do grow up fast.
Several freshwater fish are called sharks because they have a sleek body and triangular dorsal fins. Iridescent sharks might be the most shark-like in appearance. Unlike other catfish, they swim in the middle of the water column during the day.
These fish are very popular in Asia, though not for aquariums. They are farm-raised in massive ponds for food. In fact, you might have seen an iridescent shark at your local grocery store without realizing it. In the USA, they are sold as Swai, a cheap yet tasty white fish option.
- Common Names: Iridescent shark, Shark catfish, Sutchi catfish, Iridescent catfish, Swai
- Scientific Name: Pangasianodon hypophthalmus
- Origin: Southeast Asia (Mekong + Chao Phraya river)
- Length: Up to 4 feet
- Aquarium Size: 500+ gallons
- Temperament: Semi-aggressive; Schooling
- Ease of Care: Moderate
Iridescent Shark Care
Iridescent catfish are hardy, eat everything, and live for a long time. They get a moderate rating because they need aquariums far larger than most beginners can provide.
How Big Do Iridescent Sharks Get?
Baby iridescent sharks are a common sight in pet stores. They are just a few inches long and a bright, shiny purple. But a full grown iridescent shark is another matter.
Adults reach up to 4 feet long and weigh close to 100 lbs. As they grow up, they lose most of the iridescent tones. They are also schooling fish and should be kept in groups.
Worse still, they are skittish and will jump if frightened. And lastly, these fish grow up fast. Inexperienced aquarists buy one or several, thinking they will either have time to upgrade to a larger tank. Or they will rehome them at a pet store or public aquarium.
The fast iridescent shark growth rate is a major reason why they are popular as a farmed food fish. They will be a few feet long in just 2-3 years.
Pet stores and public aquariums also get requests all of the time from people looking to rehome these fish. You won’t be able to find a new home for a shark catfish that has grown too large with ease. Make sure you’re committed before buying an irredecent shark.
Here is what a 2 ½ foot long pair of albino iridescent sharks looks like.
Iridescent Shark Tank Size
When small, you should keep an albino iridescent shark in a tank appropriate for any active fish its size. The smallest seen for sale are about 3 inches long, making a 30 gallon tank the minimum for a baby.
Adults should be kept in a 500 gallon tank, minimum. These fish are ideal for custom designed enclosures this size or larger. Heated indoor ponds or outdoor ponds in warm regions like Florida are even better.
Water Conditions for Iridescent Sharks
Once you get past tank size, iridescent shark care is a simple affair. They are not at all picky when it comes to water conditions. Iridescent sharks prefer soft, acidic conditions, much like other Southeast Asian fish.
A pH of 5.5-7.0 is preferred, along with low levels of dissolved minerals in their water. That said, a shark catfish will do well even with an alkaline pH (7.0+) and moderate levels of dissolved minerals.
The water temperature is much more important, however. These are tropical fish and should be kept at 73-83℉. Cooler temperatures are stressful for iridescent catfish and will make them more susceptible to aquarium fish ich.
Iridescent sharks are not highly sensitive to ammonia and other nitrogenous waste products. But you should still aim to keep levels as low as possible since pollutants do stress them.
Shark Catfish and Aquarium Ich
These fish are ich magnets. They come from hyper-crowded fish farms where the water quality is poor. Plus, they are scaleless fish, which tend to catch ich easier. Scaleless fish are also sensitive to medications, so it’s harder to treat their ich once they catch it.
Shark catfish also tend to spread ich to other fish with ease. So choose your fish with care when shopping at your local fish store. Reject any iridescent shark with even a spot of ich.
Iridescent Shark Tank Mates
Be careful when choosing iridescent shark tank mates. When young, these fish are peaceful but predatory. Their mouths open wider than you might think. And they are fast enough to catch and eat even active fish like tetra fish and guppies.
Instead, keep a baby iridescent shark with other fish of a similar size. Or of a body shape that does not make them easy to swallow. Tiger barbs, gouramis, giant danios, corydoras, clown loaches, and plecostomus are excellent tank mates.
As they grow up, you will have to switch to larger tank mates. Full grown iridescent sharks will live peacefully alongside silver dollars, tinfoil barbs, arowanas, and freshwater stingrays. They also get along well with large, predatory cichlids like oscars and peacock bass.
What Do Iridescent Sharks Eat?
Besides their rapid growth rate, the other main reason why these fish are popular for farming is that they are not picky eaters.
Iridescent sharks will eat any kind of animal or plant matter they find. They are generalist omnivores, eating more animal protein when young. And switching to more aquatic plants as they mature.
Baby shark catfish have sharp teeth they use for catching aquatic invertebrates and smaller fish. A full grown iridescent shark doesn’t have a lot of teeth. They have grinding pads for chewing up vegetation.
Prepared foods are an excellent base for their diet. Flakes when very young, switching to a high quality pellet formula once they are large enough. Shop for brands that use whole ingredients like fish meal, squid, spirulina, etc.
Supplement this with a wide selection of fresh and frozen foods. Brine shrimp and bloodworms are some of their favorite foods when young.
As they grow larger, you can use chunks of fresh fish and shrimp. Along with bunches of soft aquatic plants like elodea and cabomba. Boiled vegetables like zucchini, spinach, and lettuce are also good for them.
Breeding Iridescent Sharks
Breeding iridescent sharks is doable but the conditions required are not something beginners can provide.
In Southeast Asia, they are farm-raised in outdoor ponds that are thousands of gallons in volume. A large amount of space allows these huge fish to school and pair off when spawning. Some farms also use hormones to encourage the fish to spawn on demand.
Unless you have a giant pond with year-round tropical temperatures, you aren’t going to breed iridescent sharks.
Conclusion
The iridescent shark is attractive when young but not a good aquarium fish for 99% of hobbyists. Shark catfish grow far too large to be housed with ease. They prefer being kept in schools, not alone. And they will eat smaller tank mates to fuel their rapid growth rate.
FAQs
Shark catfish are semi-aggressive fish. As long as they can’t eat any of their tank mates an iridescent shark will ignore it. Sometimes an iridescent shark will become a fin-nipper when kept with long-finned tank mates. They may nip a betta fish or long-finned guppy to death, even if they can’t swallow it.
Iridescent sharks are a species of large freshwater catfish, not true sharks. They are shark-like in appearance, though. Their pointed dorsal fin, forked tail, and torpedo-shaped body make them more shark-like than most “freshwater sharks.” The one freshwater species that might be even more shark-like is the bala shark (Balantiocheilus melanopterus).
Iridescent fish grow up to 4 feet long. They will also weigh almost 100 lbs when full grown.
