Iridescent shark

The iridescent shark is not a shark but a large migratory catfish of the family Pangasiidae, native to the Mekong and Chao Phraya river basins of Southeast Asia, where it is also farmed for food. Juveniles show an iridescent sheen and a dark lateral stripe, fading to plain gray as they grow enormous. It is a fast, skittish, shoaling fish that is peaceful by nature but grows far too large and nervous for typical home aquaria, often injuring itself against tank walls when startled. This species realistically requires pond-scale or public-aquarium housing measured in thousands of liters, with dim, calm surroundings to reduce panic. It is an omnivore that becomes increasingly plant- and pellet-oriented with age, taking large sinking foods, vegetables and meaty items. It is frequently sold to unaware buyers and is a classic example of a fish that outgrows its tank.