Iridescent shark

Pangasianodon hypophthalmus

Also known as Iridescent shark catfish, Sutchi catfish, Siamese shark, Striped catfish

FreshwaterFish

Iridescent shark (Pangasianodon hypophthalmus) — Trương Minh Khải · CC0

Care at a glance

Temperature: 72–79°F (22–26°C)
pH: 6.5–7.5
Adult size: 39.4 in (100 cm)
Minimum tank: 528 gal (2,000 L)
Temperament: Mostly peaceful
Social behavior: Schooling
Swim level: Bottom
Difficulty: Difficult
Breeding: No record
Rarity: Common
Origin: Native to the Mekong and Chao Phraya river basins of Southeast Asia.
Family: Pangasiidae

Overview

Be honest about the size before buying: those cute silvery 5 cm juveniles grow into a meter-long fish that outgrows almost every home tank and easily reaches 90 cm or more. It is skittish and bolts at sudden movement, often injuring itself against the glass or lid, so it needs a huge, calm tank of at least 2000 liters, really a pond or public aquarium job. It is not aggressive but will swallow anything bite-sized. Only take one on if you can house an animal this big for its 15 to 20 year life.

In the wild

In the wild this is a big-river fish that roams open channels of the Mekong and Chao Phraya in loose shoals, covering long distances. It is an active, midwater swimmer rather than a true bottom hugger, though it feeds along the bottom. It wants a long tank with lots of horizontal swimming room, gentle current, and dim, calm surroundings, at 22 to 26 degrees C.

Good to know

Pangasianodon hypophthalmus reaches around 100 cm in captivity and up to 130 cm and over 40 kg in the wild. It is farmed by the million for food across Southeast Asia, usually sold under the name basa or swai. Poor eyesight and a nervous streak make it prone to panic.

Did you know

The main welfare problem with this fish is not care difficulty but the gap between the 5 cm juvenile in the shop and the meter-long adult it becomes, which is why so many end up rehomed or dead.