pirarucu
noun
pi·ra·ru·cu pi-ˌrär-ə-ˈkü 
: 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.
Example Sentences
Recent Examples on the Web Other criminals traffic everything from gold to the prized pirarucu fish, police said. 
Luciana Magalhaes, WSJ, 18 June 2022 The reason is that pirarucu share their habitat with piranha. The Economist, 17 Oct. 2019 Whether insights from pirarucu scales will percolate into materials science remains to be seen. The Economist, 17 Oct. 2019 The Brazilian sustainable luxury label Osklen (Katie Holmes is a fan) has a new superchic pirarucu weekend bag ($1,997) that has the look of an exotic but is in fact made from fish skins. Alison S. Cohn, New York Times, 28 June 2017
Luciana Magalhaes, WSJ, 18 June 2022 The reason is that pirarucu share their habitat with piranha. The Economist, 17 Oct. 2019 Whether insights from pirarucu scales will percolate into materials science remains to be seen. The Economist, 17 Oct. 2019 The Brazilian sustainable luxury label Osklen (Katie Holmes is a fan) has a new superchic pirarucu weekend bag ($1,997) that has the look of an exotic but is in fact made from fish skins. Alison S. Cohn, New York Times, 28 June 2017 Word History
Etymology
Portuguese, from Tupi pirawrukú, from pirá fish + urukú annatto
First Known Use
1840, in the meaning defined above