How to Identify Pacu

To identify Pacu (Piaractus mesopotamicus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Adults typically have a silvery-gray to dark gray body, often with a darker dorsal region and lighter belly. Juveniles may exhibit more pronounced dark spots or bands, which fade with age. Fins are generally dark, sometimes with reddish tints, especially in the pectoral and anal fins.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Deep, laterally compressed body, Small, cycloid scales, Adipose fin present, Strong, molar-like teeth, resembling human dentition, adapted for crushing seeds and nuts, Large, prominent eyes

Dorsal fin

Single, relatively short dorsal fin, typically with 10-11 soft rays.

Tail fin

Large, deeply forked caudal fin.

Pectoral fin

Well-developed pectoral fins, often with a reddish hue.

Distinctive fins

Presence of a small, fleshy adipose fin between the dorsal and caudal fins, characteristic of characins.

Identification Tips

1. 1

   Teeth

   The most distinctive feature is its human-like, molariform teeth, which are broad and flat, designed for crushing. This differentiates it from piranhas, which have sharp, pointed, interlocking teeth.

2. 2

   Body Shape and Size

   Piaractus mesopotamicus has a deep, compressed body and can grow to a substantial size (up to 70 cm and 20 kg), larger than most piranha species.

3. 3

   Coloration

   Adults are generally silvery-gray to dark gray, lacking the vibrant red or orange belly often seen in red-bellied piranhas (Pygocentrus nattereri).

4. 4

   Adipose Fin

   Like other characins, it possesses a small, fleshy adipose fin, which is a key family characteristic.

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