How to Identify Silver Dollar

To identify Silver Dollar (Metynnis argenteus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Predominantly silvery, often with a metallic sheen. Juveniles may exhibit faint vertical bars or small dark spots, which typically fade with age. The fins are usually translucent, sometimes with a reddish tint, especially in males during breeding.

Scale type

cycloid

Mouth position

superior

Distinctive features

Highly compressed, disc-shaped body, resembling a silver coin., Large, reflective scales., Small, upturned mouth., Adipose fin present.

Dorsal fin

Single, relatively short-based dorsal fin positioned mid-body.

Tail fin

Forked caudal fin.

Pectoral fin

Moderately sized, clear pectoral fins.

Distinctive fins

Anal fin is long, extending from behind the pelvic fins to the caudal peduncle. Males often develop a reddish hue on the anal fin and sometimes the dorsal fin, and may have small hooks on the anal fin rays during breeding.

Identification Tips

1. 1

   Body Shape

   Look for the characteristic, almost perfectly circular and highly compressed body, which is the most defining feature.

2. 2

   Coloration

   The uniform, bright silver coloration with a metallic sheen is a key identifier. Absence of prominent patterns or large spots (which differentiate it from some other Metynnis species).

3. 3

   Fin Structure

   Observe the long anal fin and the presence of an adipose fin. In mature males, the reddish tint and potential hooks on the anal fin are diagnostic.

4. 4

   Mouth Position

   The small, slightly upturned mouth is adapted for surface feeding and grazing on vegetation.

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