Pirarucu

Water parameters

Minimum tank: 20000 L per individual at harvest size.

Feed and growth

Feed protein

45% target

Daily feed (warm)

1.00% of body weight

Daily feed (cool)

0.40% of body weight

Max density

35 g per litre

A 200000 g adult eats about 2000.0 g of feed per day at optimum. 10 fish at adult size: ~20000 g daily.

Legality

Rules vary by jurisdiction and change over time. Verify with your local fisheries or wildlife authority before stocking.

Unlisted jurisdictions default to "check local regulations".

Origin and habitat

Native to the Amazon basin, living in floodplain lakes, oxbows and slow river channels across Brazil, Peru, Colombia, Guyana and neighbouring countries. It ranks among the largest freshwater fishes on earth: commonly around 2 m, with historical records near 3 m or more and weights to about 200 kg. The genus was long treated as one species, but a 2013 revision recognised five, so some stock formerly called A. gigas may belong to related Arapaima species. The fish is an obligate air-breather: it must rise every few minutes, up to roughly 20, to gulp air through a swim bladder that works as a lung, with a loud surface gulp that carries a long way. That adaptation lets it thrive in the warm, oxygen-poor floodplain water it favours. The flesh is white, firm and mild, with large bones that strip out cleanly, and it sells at premium prices in Brazilian and Peruvian markets. Heavy overfishing through the twentieth century cut wild stocks sharply; the species sits on CITES Appendix II and is listed by the IUCN as Data Deficient. Community-managed fisheries and expanding farming have helped some populations recover.

Climate and outdoor ponds

Climate

tropical (needs warm water year-round)

USDA zones

11–13 (winter low around 4°C or warmer)

Heating needed

yes

Cooling needed

no

Care notes

A giant tropical species for large-scale aquaculture, not a fit for ordinary home aquaponics given its eventual size. Juvenile growth is among the fastest recorded in any fish, often 10–15 kg in the first nine to twelve months on high-protein feed. Protein demand is steep early, near 55 to 57 percent for small juveniles, easing to about 45 percent at grow-out. Feed conversion is striking: well under 1 in early stages, rising to roughly 1.8 to 2.0 on commercial grow-out diets. Warm water drives that growth, so the fish needs heated systems in the upper 20s Celsius and does poorly when cool. Because it breathes air, dissolved oxygen in the tank is not a limiting factor, a real advantage in warm low-oxygen systems. Unlike most predators, arapaima show little cannibalism within a single year class and stay gregarious during grow-out, which removes a problem common to piscivore culture. They still need very large tanks or ponds; commercial grow-out uses ponds of roughly half a hectare to a couple of hectares. To date only Brazil and Peru report meaningful output, on the order of several thousand tonnes a year. Moving live fish across borders needs CITES permits, and several US states restrict or ban possession, so check local rules before stocking.

Further reading

• Aquaponics water chemistry: balancing pH for fish and plants
• Fish for aquaponics: tilapia vs everything else