Arapaima (8-9”)

Arapaima Overview

• Scientific Name: Arapaima gigas (and closely related A. leptosoma, A. mapae, etc.)

• Common Names: Arapaima

• Family: Osteoglossidae (related to arowanas)

• Origin: Amazon and Essequibo River basins (South America)

• Adult Size: Up to 10–15 feet in the wild; 6–8 feet in captivity.

• Weight: Can exceed 400 lbs 

• Lifespan: 15–20+ years in captivity

Natural Environment:

• Habitat:

  • Slow-moving, oxygen-poor rivers, flooded forests, and lakes.

  • Frequently surfaces to breathe air via a modified swim bladder.

• Water Conditions:

  • Temperature: 75–86°F (24–30°C)

  • pH: 6.0–7.5

  • Soft, tannin-stained (blackwater) environments are common

• Behavior:

  • Solitary or found in pairs

  • Top- and mid-level swimmer

 Diet

Arapaimas are obligate carnivores and opportunistic ambush predators:

• Wild Diet: Fish, crustaceans, insects, birds, and small mammals near the water's surface

• In Captivity:

  • Whole fish (e.g., tilapia)

  • Shrimp, squid, mussels

  • Pellets formulated for carnivorous fish (for smaller individuals)

  • Occasional treats like chopped meat, though this should be limited due to fat content

They have a strong feeding response and may lunge or leap to catch prey.

Recommended Aquarium Size

Arapaima are one of the largest growing species of freshwater fish, therefore bringing them into a home aquarium should be taken with great consideration. 

• Minimum Recommended Size:

  • For juveniles: 200-400 Gallons — but outgrown quickly

  • For adults: 10,000+ gallons with considerable length.

• Tank Features:

  • Extremely strong, sealed enclosure

  • Oxygenated water with surface access for air breathing

  • No sharp objects or decor — they can injure themselves easily

  • Secure lid: they can launch themselves out of the water with great force.

Important Considerations

• Legality: Banned or restricted in many regions due to their size and ecological impact. Make sure to check your states laws*

• Air Breather: Arapaima are labrinyth breathers. They require constant surface access or can drown.

• Temperament: Usually calm but can become aggressive, especially if confined or startled/stressed.

• Feeding Hazard: Strong jaws — feeding by hand is dangerous. They are incredibly strong fish that can cause injury during tank transfers