TankBud

Black pacu

Colossoma macropomum

FreshwaterFish

Black pacu (Colossoma macropomum)
Bloopityboop · CC BY-SA 4.0

Care at a glance

Temperature
72–82°F
22–28°C
pH
5.5–7.5
Adult size
39.4 in
100 cm
Minimum tank
660 gal
2,500 L
Temperament
Mostly peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Middle
Diet
Omnivore
Difficulty
Difficult
Breeding
No record
Rarity
Very rare
Family
Serrasalmidae
Origin
South America

Overview

The black pacu, or tambaqui, is a giant fish that grows far too large for the average home aquarium. It is a project for experienced keepers with a heated indoor pond or a public-scale tank.

Did you know

A black pacu has flat, squared teeth that look unsettlingly human. It uses them to crack the hard fruit and nuts that drop into the flooded forest. In the wild it also acts as a seed disperser, carrying seeds far downstream.

Caring for the black pacu

A single adult black pacu needs enormous space, at least 660 gal (2,500 L) and ideally much more. Run strong, clean filtration that can cope with its heavy waste. Only take one on if you can meet its lifelong size and space needs.

Keep the water at 72 to 82°F (22 to 28°C) with a pH of 5.5 to 7.5. Black pacu are hardy across a wide range, but they produce a lot of waste. Large, frequent water changes matter far more than fine-tuning the chemistry.

Feed a mostly plant-based diet of fruit, vegetables and sinking pellets, with occasional protein. It is usually kept alone, since its sheer bulk rules out most tank mates. It is not an aggressive fish by nature.

Black pacu are not bred in home aquariums. Farms across the tropics breed them commercially using hormone-induced spawning, so there is no meaningful hobby breeding record.

Good to know

The black pacu belongs to the family Serrasalmidae, which also holds the piranhas, but it is a peaceful giant rather than a hunter. Young fish are often confused with their piranha relatives. It is one of the largest scaled fish in the Amazon, commonly passing 60 cm. In the wild it can weigh around 30 kg, and published records reach near 108 cm.

In the wild

Tambaqui are native to the Amazon and Orinoco basins of South America, where they roam flooded forests and main river channels. During the annual floods they move into inundated woodland to feed on falling fruit and seeds, which shapes their whole biology.

Common questions

What size tank does a black pacu need?

A black pacu needs at least 660 gal (2,500 L). It spends most of its time in the middle.

What temperature and pH does a black pacu need?

A black pacu is comfortable at 72–82°F (22–28°C) with a pH of 5.5–7.5.

What does a black pacu eat?

A black pacu eats a mostly plant-based diet of fruit, vegetables and sinking pellets. Give it some protein now and then.

How big does a black pacu get?

An adult black pacu reaches about 39.4 in (100 cm).

How does a black pacu breed?

Black pacu are not bred in home aquariums. Farms across the tropics spawn them commercially with the help of hormones.

Related species