Arapaima

The Arapaima is a giant freshwater fish native to the Amazon basin, widely recognized as one of the largest freshwater fish species on Earth, with confirmed lengths exceeding 2 meters. It belongs to the same ancient bony-tongued fish family as arowanas and possesses a modified swim bladder that functions as a primitive lung, allowing it to breathe atmospheric air, an adaptation to the frequently low-oxygen waters of Amazonian floodplains. Several species are now recognized within the genus Arapaima, found across Brazil, Peru, Guyana, and neighboring countries. Populations have historically declined in parts of its range, leading to conservation and management programs in several countries.

Recognize an Arapaima by these features:

• Size: exceptionally large body, commonly 2 to 3 meters in adults
• Body shape: elongated, cylindrical, and heavily built with a relatively small head
• Scale coloration: dark olive-grey scales forward on the body, transitioning to scales edged in vivid red toward the tail
• Scales: thick, bony, overlapping armor-like plates
• Dorsal and anal fins: set far back near the tail, mirroring each other

Its massive size combined with red-edged rear scales and the habit of surfacing to gulp air make it unmistakable among Amazonian freshwater fish.

Arapaima inhabit slow-moving rivers, oxbow lakes, and seasonally flooded forest habitats throughout the Amazon and Essequibo river basins of South America, including Brazil, Peru, Guyana, and Colombia. They favor warm, still or slow-flowing water, often in areas with low dissolved oxygen where their air-breathing capability provides a significant advantage over strictly gill-breathing fish. During the flood season they move into inundated forest to feed, retreating to permanent river channels and lakes as water levels drop. Water temperatures in their habitat typically range from 25 to 30 degrees Celsius year-round.

Arapaima must surface every 5 to 15 minutes to gulp air using their lung-like swim bladder, a behavior that makes them relatively easy to observe compared to strictly aquatic fish. They are generally solitary or found in small groups, becoming notably territorial and protective during the breeding season. Spawning typically occurs at the start of the flood season, with both parents guarding the nest and, after hatching, the young often forming a tight school that stays close to a guarding parent for protection from predators. As an apex predator in its ecosystem, the Arapaima plays a significant role regulating populations of smaller fish in Amazonian floodplain habitats.