Not only is the Mekong giant catfish one of the world's largest freshwater fish, surprisingly it's also one of the fastest growing. While you might na­turally assume their massive growth occurs gradually as they age, especially considering these catfish have an average life span of more than 60 years (assuming nothing nefarious interferes), that's not the case.

Mekong giant catfish are commonly cited as having a maximum size of 3 meters and 300 kilograms (approximately 10 feet and 660 pounds). But in what's got to be the growth spurt to end all growth spurts, Mekong giant catfish hatchlings (called fry) that have been bred in captivity have averaged a 400 percent growth rate in a mere 4 months. When born in natural habitats, by the time the fish are three to five years old, they reportedly weigh about 330 to 440 pounds (150 to 200 kilograms).

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