Pacu (8”)

Scientific Name:

Piaractus brachypomus

Maximum Size and Lifespan:

• Maximum Size: Up to 36-48 inches (76 cm) in captivity,

• Lifespan: 20–25+ years with proper care

Recommended Aquarium Size:

• Tank Size: Minimum 500 gallons (1,900+ liters) for a single adult

  • Juveniles can be kept in smaller tanks (at least 75–180 gallons), but will rapidly outgrow them

• Pacus are strong swimmers and require long, wide tanks for movement

Water Changes and Care:

• Water Temperature: 74–82°F (23–28°C)

• pH Range: 6.5–7.5

• Water Changes:

  • 40-80% weekly to maintain stable water quality due to their large biomass

• Filtration:

  • Heavy-duty canister or sump filtration is crucial

  • Use multiple filters and/or additional powerheads for proper circulation

• Pacus are sensitive to ammonia and nitrite spikes, so excellent biological filtration is key

Tankmates:

• Best kept alone or with large fish like:

  • Silver Arowanas, Giant Gouramis, Large Plecos, Datnoids, Peacock Bass, Oscars (Always mix pacu with caution they can be nippy with their blunt teeth.

• Avoid  small species (they may be mistaken for food)

• Caution: Pacus can accidentally injure or outcompete others for food due to their size and speed

Diet:

• Omnivorous, leaning heavily toward herbivory

• Staple Foods:

  • High-quality pellets for herbivores/omnivores. They will eat just about anythin g offered.

  • Fresh vegetables: spinach, peas, lettuce, zucchini, cucumber

  • Occasional protein: Tilapia and shrimp (in small amounts only)

• Feed 1–2 times daily with 1 day of fasting to avoid bloat

Overview:

Pacus are large, intelligent South American fish, resembling the Piranha but lacking its aggressive carnivorous nature. While popular due to their peaceful nature and hardy disposition, they grow extremely large, leading to many being surrendered or improperly housed. These gentle giants require serious commitment, advanced equipment, and very large aquariums or indoor ponds to thrive in captivity.

Natural Environment:

• Habitat: Amazon and Orinoco river basins

• Found in floodplains, slow-moving rivers, flooded forests

• Water is warm, tannin-rich, and often slightly acidic

• In the wild, they feed on fruits, seeds, nuts, and plant matter that fall into the water

Breeding:

• Extremely difficult in home aquariums

• Require seasonal flooding conditions and large open water systems to stimulate spawning

• Commercial breeding is done in large outdoor ponds with hormonal induction

• No confirmed reports of natural breeding in private hobbyist tanks

• If attempted, breeding would require multiple adults, massive tank space, and fine-tuned water parameters

If you’re considering keeping a Regular Pacu, remember: They are not suitable for small or even medium-sized aquariums long-term. They are best suited to dedicated public aquaria or private indoor ponds with adequate planning for their full adult size.