Definition of pirarucu
: a large-scaled, predatory, freshwater fish (Arapaima gigas of the family Arapaimidae) of the rivers of northern South America that is an esteemed food fish, has a toothed tongue, and may reach a length of nearly 10 feet (3 meters) and a weight of over 300 pounds (136 kilograms) but is typically smaller
Note:
The pirarucu has been placed especially formerly in the same family (Osteoglossidae) as the arowanas.
