What is the largest species of freshwater fish in the world?

The beluga sturgeon in Russia is the largest freshwater fish in the world. This massive fish can reach over 15 feet long and weigh upwards of 2,500 pounds. The largest recorded beluga sturgeon was almost 20 feet long and over 7,000 pounds. These fish also have a long lifespan, living to 100 years and older.

Beluga sturgeon are euryhaline, meaning they can swim freely between salt and fresh water. Humans consider their eggs a delicacy and have overfished these massive monster-sized fish to get them, leaving the beluga sturgeon endangered with little chance of survival. Beluga sturgeon eggs are the most prized and rare type of caviar, favored for the delicate skin, but due to the endangered status of the fish, beluga sturgeon caviar is illegal in the United States.