Hydrolycus scomberoides, commonly known as the "Payara" or "Vampire Fish," is a species of predatory freshwater fish found in South America, mainly in the Amazon and Orinoco River basins.

This fish is known for its ferocious predatory behavior, razor-sharp teeth, and unique appearance. It has a long, slender body with silver scales, and a large head with elongated jaws filled with numerous sharp, interlocking teeth. The teeth can be up to 4 cm in length, which allows the Payara to efficiently hunt and eat other fish, crustaceans, and even birds that venture too close to the water surface.

Payaras can reach up to 1.2 meters (4 feet) in length and weigh over 15 kilograms (33 pounds). They are highly valued by recreational anglers for their strength and fighting ability, but they are also kept in large public aquariums around the world because of their impressive appearance and predatory behavior.

Due to their large size and aggressive nature, Payaras require a spacious aquarium with high water quality. They should be fed a diet consisting of live or frozen fish, as well as crustaceans and other meaty foods. They are not recommended for beginner fish keepers or for small home aquariums.