Pirarucu

About

Pirarucu (Arapaima gigas) are genuinely ancient-looking fish, and for good reason. Their lineage traces back millions of years. Reaching lengths of five feet and well beyond in the wild, they rank among the largest purely freshwater fish on the planet, with some individuals reportedly exceeding ten feet. They come from the floodplains of the Amazon basin, where seasonal water levels swing dramatically and dissolved oxygen can drop to almost nothing. To cope, pirarucu evolved obligate air-breathing, surfacing roughly every fifteen minutes to gulp air with an audible, booming sound that reportedly carries across considerable distances. Their gills function mainly in juveniles; adults rely almost entirely on their specialized swim bladder to extract oxygen from the air. In the wild they are deliberate, patient predators, picking off fish with efficient, well-timed strikes. Pirarucu are also surprisingly attentive parents, building shallow nests in sandy substrate and actively guarding eggs and fry. Wild populations have declined significantly from overfishing, particularly near densely settled parts of the Amazon. In captivity, these fish are strictly a project for the most serious advanced keepers with truly massive, purpose-built facilities. Even public aquariums struggle to house adults appropriately. This is not a community fish, and it is absolutely not a casual purchase.