Arapaima

What it is

The arapaima is one of the largest freshwater fish on Earth. Adults typically measure two metres but can reach four and a half metres. The body is streamlined with gray or gray-green skin that turns reddish in mature males. Its scales form a tough, armor-like layer made of collagen and mineralized material. This structure protects the fish from predators like piranhas. The dorsal and anal fins are positioned near the tail. It belongs to an ancient group of bony-tongued fishes that retain primitive traits.

Where it lives

This species lives in the Amazon and Tocantins-Araguaia river basins across Brazil and Peru. It prefers shallow waters, flooded forests, and lakes. Populations have expanded into non-native areas due to aquaculture escapes. In Peru and Bolivia, they inhabit connected river systems like the Beni and Madre de Dios. Small groups also exist in Ecuador, Colombia, Guyana, and parts of East Asia such as Indonesia. They move between river channels and floodplains depending on water levels.

How it lives

Arapaimas are specialized carnivores that eat other fish, insects, birds, and floating seeds. They must surface every five to fifteen minutes to gulp air using a modified swim bladder. Juveniles start as water-breathers but develop lung-like tissue within days. Males provide parental care and use head secretions to communicate with offspring. The fish migrates seasonally to flooded forests for feeding and safety. High water densities support breeding activities, while low waters concentrate them in isolated lakes.

Breeding and life cycle

Maturity occurs at five years old. Spawning happens during low water periods from August to March. Pairs dig nests in the substrate and lay eggs in small batches of fewer than five hundred. Males guard the young for three to six months. Females have only a left ovary, while males possess a single testis. Red coloration in males signals age and aids sexual selection. This batched strategy reduces total egg loss during unpredictable environmental changes.

Fish and people

Local communities harvest arapaimas for food and income. A sustainable management programme in Brazil recovered stocks from two thousand five hundred to over one hundred seventy thousand individuals between nineteen ninety-nine and twenty seventeen. Illegal fishing remains common in the lower Amazon. The fish is also farmed for meat and kept as an aquarium pet in Europe, North America, and Asia. In some regions, it is considered an invasive threat to native ecosystems due to escaped farm stock.

Status and threats

The species is listed as Data Deficient by the IUCN due to limited population data. Genetic diversity has suffered from habitat loss and historical overexploitation. Fishing bans in Brazil during the late nineteen nineties allowed stocks to rebound significantly. However, illegal harvesting continues to pressure wild populations. Transporting specimens for aquaculture causes genetic homogenization. Conservationists monitor heterozygosity levels to prevent inbreeding and ensure long-term evolutionary potential.

Relatives and look-alikes

The genus Arapaima was once thought to contain only this species. Recent studies identify additional members like Arapaima leptosoma and Arapaima agassizii. Fossil evidence from Colombia suggests similar species existed thirteen million years ago. The arapaima is often confused with other large freshwater giants but is distinct due to its air-breathing physiology and armored scales. It shares its ancient lineage with other osteoglossomorph fishes found in tropical regions.

Questions people ask about Arapaima

Good reading and sources

• Arapaima gigas on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data