Tambaqui

The tambaqui is a large species of freshwater fish in the family Serrasalmidae. It is native to tropical South America, but kept in aquaculture and introduced elsewhere. It is also known by the names black pacu, black-finned pacu, giant pacu, cachama, gamitana, and sometimes as pacu (a name used for several other related species). The tambaqui is currently the only member of Colossoma, but the Piaractus species were also included in this genus in the past.

Source: Wikipedia