Black Pacu

Care at a glance

Overview

The black pacu, or tambaqui, is a giant fish that grows far too large for the average home aquarium and is really a project for a heated indoor pond or a public-scale tank. A single adult needs enormous space, so plan for at least 2500 liters and ideally much more, with powerful filtration to cope with its heavy waste. It is usually kept alone, as its sheer bulk rules out most tankmates, though it is not an aggressive fish by nature. Feed a mostly plant-based diet of fruit, vegetables, and sinking pellets, with occasional protein. Only take one on if you can meet its lifelong size and space needs.

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. Keep them warm at 22 to 28 C with a pH from about 5.5 to 7.5 and strong, clean filtration. They are hardy across a wide range but produce a lot of waste, so large, frequent water changes matter far more than fine-tuning the chemistry.

Good to know

The black pacu belongs to Serrasalmidae, the family that also holds piranhas, but it is a peaceful giant rather than a hunter. It is one of the largest scaled fish in the Amazon, commonly passing 60 cm and reaching close to a metre and around 30 kg in the wild, with published records near 108 cm. Its jaws carry broad, molar-like teeth built for crushing nuts and seeds rather than tearing flesh. It is not bred in home aquaria, though it is farmed commercially across the tropics using hormone-induced spawning, so there is no meaningful hobby breeding record.

Did you know

A black pacu has flat, squared teeth that look unsettlingly human, which it uses to crack the hard fruit and nuts that drop into flooded forest. In the wild it acts as a seed disperser, carrying seeds far downstream, and as a youngster it is often confused with the piranhas it is related to.

Related species

• 

  Red-bellied pacu

  Piaractus brachypomus

  34.6 in (88 cm)1,057 gal (4,000 L)73–82°F (23–28°C)

• 

  Tiger pacu

  Acnodon normani

  5.1 in (13 cm)46 gal (175 L)72–82°F (22–28°C)

• 

  Disk tetra

  Myleus schomburgkii

  15.7 in (40 cm)170 gal (645 L)73–81°F (23–27°C)
• Black piranha

  Serrasalmus rhombeus

  15.7 in (40 cm)106 gal (400 L)75–82°F (24–28°C)

• 

  Red-bellied Piranha

  Pygocentrus nattereri

  12.6 in (32 cm)160 gal (605 L)75–82°F (24–28°C)

• 

  Redhook

  Myloplus rubripinnis

  9.8 in (25 cm)70 gal (265 L)73–81°F (23–27°C)