Scientific name: Colossoma macropomum
Continent: South America
Food & feeding: Plankton, insects, snails, plants, fruits and grains.
Conservation status: Data Deficient
Relatives: Red-bellied piranha
Description: The second largest fish in the Amazon, reaching up to 1 m in length and weighing 30 kg. The colouration of the fish differs depending on its water type; those living in the blackwater are dark and those living in turbid waters are much lighter. Pacu are Similar in shape to a piranha, and usually has small black fins. It has unique teeth that look superficially like human teeth; adapted for crushing tough seeds and nuts. Their gill-rakers capture zooplankton in the slow flowing waters of the Amazon.
Lifestyle: Adult pacu are usually solitary and live in the flooded forests. They have a keen sense of smell and vision to help them locate their favourite food; large nuts and seeds. They have a preference for the seeds of the rubber tree and will wait underneath trees that are dropping seeds. Their diet allows them to store up to 10% of their body weight as fat.
Family & friends: Usually solitary
Keeping in touch: Pacu have a special line of sensors down the sides of their bodies, called the lateral line system. This picks up changes in water pressure, currents and the movements of other animals in the water.
Growing up: Eggs are laid in the white-water river channels, which the young will use as a nursery. Young pacu are sustained on a diet of zooplankton and some fruit material. As the young have a large energy demand then the adults, they feed on constantly available zooplankton. Adults mainly feed on the seasonal fruits. Young take a long time to reach maturity, once they are 55 cm in length; they leave the white water floodplains and enter the blackwater.
Conservation news: Pacus are often kept as pets, Bristol zoo’s collection are all donations from public.