Pirarucu

Quick facts

Adult size

250 cm, 100000 g typical harvest weight

Days to harvest

540 to 1095 days from fingerling

Lifespan (max)

up to 20 years

Diet

carnivore

Temperature class

warm-water

Difficulty

advanced

Water parameters

Temperature range

24–32°C (optimum 28°C)

pH

5.5 to 7.5

Hardness

1 to 15 dGH

Minimum tank

20000 L per individual at harvest size

Feed and growth

Feed protein

45% target

Daily feed (warm water)

1.00% of body weight per day

Daily feed (cool water)

0.40% of body weight per day

Max stocking density

35 g per litre of system water

A 100000g adult eats about 1000.0 g of feed per day at optimum temperature. For a roster of 10 fish at adult size, that's around 10000 g of feed daily.

Legality

Aquaculture and possession rules vary by jurisdiction and change over time. This table reflects regulations as of the verified date on each row. Verify with your local fisheries or wildlife authority before stocking.

Jurisdictions not listed here default to "check local regulations". A non-listing is not a green light; rules in your specific county or municipality may apply.

Habitat and origin

Native to the Amazon River basin, including floodplain lakes, oxbow lakes, and slow-moving river channels across Brazil, Peru, Colombia, and Guyana. The species (Arapaima gigas) is one of the largest freshwater fish in the world, reaching 2–3 m and over 200 kg. Pirarucu is an obligate air-breather that must surface every 10-20 minutes to gulp atmospheric air using a modified swim bladder that functions as a lung. This air-breathing makes it highly tolerant of low dissolved oxygen in the warm, stagnant floodplain waters it inhabits. The flesh is white, firm, boneless (the bones are large and easily removed), and mild-flavored, commanding premium prices in Brazilian markets ($10-20/kg). Wild pirarucu populations were severely overfished during the 20th century, and the species is CITES Appendix II listed. Managed community-based fishing programs and growing aquaculture production (primarily in Brazil and Peru) have stabilized some populations.

Climate and outdoor ponds

Climate classification

tropical (needs warm water year-round)

Outdoor pond zones (USDA)

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

Heating in a temperate climate

Required for year-round operation

Cooling in a temperate climate

Not required

Zone bounds reflect year-round outdoor pond viability with no active heating. Anywhere outside the bounded zone, the species can still be kept in an indoor heated tank or a seasonally-managed system. Verify your specific microclimate, as a sheltered yard zone can run a half-zone warmer than the regional rating.

Care notes

A large-scale tropical aquaculture species, not suited to typical home aquaponics due to the enormous size of the fish. Pirarucu grow fast: 8–10 kg in the first year under good conditions, reaching 15–20 kg in 18-24 months. FCR on high-protein pellet (40-48% protein) is 1.3-1.8, excellent for a fish of this size. Temperature: 25–30°C year-round; below 20°C they stop feeding, below 15°C they die. The air-breathing adaptation means dissolved oxygen in the water is not a limiting factor, which is a genuine advantage in warm systems where oxygen saturation is naturally low. Stocking density: 10-20 g/L for grow-out, but each fish occupies substantial individual volume (a 10 kg fish in 500 L). Tank or pond size must be massive: 5,000 L for even a small group, and commercial ponds are typically 0.5-2 hectares. Pirarucu are predatory; they eat fish, crustaceans, and pellets. Mixed size classes are cannibalistic. The species is legally restricted in many countries due to CITES listing; international trade in live specimens requires permits. In Brazil, aquaculture is legal and growing rapidly, with several thousand tonnes produced annually. For tropical aquaponics at commercial scale in South America, pirarucu represents a premium product, but the size requirements make it impractical for most operators.

Further reading

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