The Arapaima is a Hardmode enemy that spawns in water pools within the Jungle and Underground Jungle biomes. They swim much faster than most fish. Although dealing high damage, this enemy has no knockback resistance, so high knockback weapons are useful.
The Arapaima can jump from the water, and therefore is able to attack players on land close to the water. It will not die naturally outside of the water, despite being a fish.
- Arapaima are the largest freshwater fish native to South America, sometimes reaching lengths of more than 2 meters (6.5 feet).
- The Bestiary entry for the Arapaima: "These enormous fish thrive in the jungle waters near veins of unstable magicks, which make them unusually strong and hostile."