• Scientific name: Colossoma macropomum
• Common name: Giant pacu, Black-finned pacu, Black-finned colossoma
• Synonyms: Colossoma nigripinnis, C. oculus, Myletes nigripinnis, M. oculus, Piaractus nigripinnis
• Group: Characins
• Habitat: South America, Brazil
• Size: over 60 cm
• Biotope: Young stay in Black waters of flood plains until maturity, adults in open water and flooded forests.
• Social behavior: A peaceful species, it likes plants.
• Diet: Primarily herbivorous, but basicly eats anything
• Breeding: In large tanks ocassionally
• Tank: Minimum 500 litres
• Population: 5-6 fish for 1200 litres
• Decoration: Requires a roomy tank with plants, roots and other places to hide. The fish become nervous and uneasy in a small tank.
• Temperature: 22-28°C
• pH: 6,5-7
• Hardness: 1-20 NK°
• Lifespan: 15-20 years

Description: Similar in shape to the piranha and part of the source of the confusion the pacu is a tall, laterally compressed fish with large eyes and a slightly arched back. Body color is black to gray with spots in its mid body. All the fins are black and the pectoral fins are small. The black pacu will live for over 20 years in the wild and can possibly live that long in captivity if they are well cared for.

The dorsal fin has a sharper extension and the anal fin is toothed on the male. Little is known of their breeding habits, due to the large size and space requirements