Colossoma

Known as the tambaqui in its native countries, this is the second largest species of scaled fish found in the Amazon basin. This alone should tell you much of what you need to know about its suitability as an aquarium inhabitant. In reality, it's debatable as to whether the species should be considered an aquarium subject at all. While pacu rarely reach their maximum size in captivity, they're still easily capable of growing to a couple of feet in length. The myth that fish will only g...