How to Identify Black Pacu

To identify Black Pacu (Colossoma macropomum), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Adults are typically dark grey to black dorsally, fading to a lighter grey or silvery-white ventrally. Juveniles often exhibit distinct black spots or blotches on their flanks, which fade with age. The operculum and fins can also be dark.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Deep, laterally compressed body, Large, robust head with a prominent snout, Strong, human-like molariform teeth adapted for crushing seeds and nuts, Relatively small, cycloid scales, Adipose fin present

Dorsal fin

Single, relatively short dorsal fin with 11-13 soft rays, positioned mid-body.

Tail fin

Large, deeply forked caudal fin, often dark or black.

Pectoral fin

Well-developed pectoral fins, typically dark.

Distinctive fins

Presence of a small, fleshy adipose fin between the dorsal and caudal fins, characteristic of characins. Anal fin is relatively long with 24-28 rays.

Identification Tips

1. 1

   Teeth

   Examine the teeth. Black Pacu have distinctive, blunt, human-like molariform teeth, unlike the sharp, pointed teeth of piranhas. This is the most reliable distinguishing feature.

2. 2

   Body Shape and Size

   Black Pacu are very deep-bodied and can grow to immense sizes (up to 1.1 meters and 44 kg), significantly larger than most piranha species.

3. 3

   Coloration (Juveniles vs. Adults)

   Juveniles often have dark spots on their flanks, which fade as they mature into the uniform dark coloration of adults. Piranhas typically retain more distinct patterns or have a more silvery/reddish hue.

4. 4

   Adipose Fin

   Like all characins, they possess a small, fleshy adipose fin between the dorsal and caudal fins.

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