Red-bellied Pacu

Piaractus brachypomus

Photo of aquarium fish Red-bellied Pacu
Natural range
  • Amazon River Basin
  • Bolivia
  • Brazil
  • Colombia
  • Peru
  • Uruguay
  • Venezuela
Characins Conservation status: Least concern LC

Family:Piranhas (Serrasalmidae)

Other scientific names: Colossoma bidens, Colossoma brachypomum, Colossoma branchypomus, Colossoma paco, Myletes bidens, Myletes brachypomus

The Red-bellied Pacu, scientifically known as Piaractus brachypomus, belongs to the subfamily Serrasalminae. This fish rarely becomes a resident of home aquariums, mainly due to its impressive size and rather modest coloration. However, it is in demand among certain (wealthy) enthusiasts who are looking for a safe alternative to the Piranha, which the Pacu closely resembles in appearance. In many tropical and subtropical countries, the sale of this species is prohibited. The reason for this is aquarists who release the fish into natural bodies of water when they tire of them. The Pacu successfully adapts to the new environment, disrupting the ecological balance and displacing local species.

Required aquarium volume
from 2550 L
Size in aquarium
60 – 88 cm
Temperature
23 – 28 °C
Temperament
Semi-peaceful
Parameters
Temperature23 – 28 °C
Water pHAcidic (4.8) – Neutral (7.5)
Water dHVery soft (1) – Hard (15)
Water salinityno salt (freshwater)
Size in aquarium60 – 88 cm
Lifespan28 years
TemperamentSemi-peaceful
Toward small fisha risk to small fish
Required aquarium volumefrom 2550 L
Lightingdimmed or moderate
Substratesoft peat-based
Water flowweak or moderate
Swimming levelmiddle level
FeedingPlant-based
KeepingBoth solitary and in group
Jumpinglow

Frequently asked questions

The essentials: size, tank volume, water parameters and care

How big does Red-bellied Pacu get?

An adult reaches 60–88 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.

What size aquarium does Red-bellied Pacu need?

The recommended volume is 2550 L. A smaller tank speeds up nitrate build-up and raises stress levels.

What water parameters does Red-bellied Pacu need?

Temperature 23–28 °C, pH 4.8–7.5, hardness 1–15 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.

How long does Red-bellied Pacu live?

Around 28 years when kept properly. Lifespan depends directly on tank volume, water quality and a varied diet.

Is Red-bellied Pacu aggressive?

Temperament: semi-peaceful (dangerous to smaller ones). Not a predatory species, but small fish that fit in its mouth will eventually be eaten.

How many Red-bellied Pacu should be kept together?

Recommended setup: both solitary and in group (flexible). Ignoring this is a common cause of stress and disease.

What does Red-bellied Pacu eat?

Diet type: plant-based (algae, vegetables). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.

What is the scientific name of Red-bellied Pacu?

The scientific name of the species is Piaractus brachypomus, family Piranhas (Serrasalmidae). It also appears in the literature as: Colossoma bidens, Colossoma brachypomum, Colossoma branchypomus.

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