How to Identify Banded Astyanax

To identify Banded Astyanax (Astyanax fasciatus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Silvery body, often with a yellowish or greenish tint dorsally. A prominent dark, often iridescent, humeral spot (shoulder spot) is typically present, sometimes extending into a faint lateral stripe that may or may not reach the caudal peduncle. Fins are hyaline (clear) to yellowish, sometimes with reddish tints, especially in breeding males. The caudal fin often has a dark blotch at its base.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Deeply forked caudal fin, Adipose fin present, Two rows of teeth in the premaxilla, Prominent humeral spot, often vertically elongated or diamond-shaped, Lateral line complete

Dorsal fin

Typically 10-11 rays, relatively short and high.

Tail fin

Deeply forked, with pointed lobes.

Pectoral fin

Relatively short, 11-13 rays.

Distinctive fins

Adipose fin present between the dorsal and caudal fins, characteristic of characins.

Identification Tips

1. 1

   Humeral Spot

   Look for a distinct, often vertically elongated or diamond-shaped dark spot on the side of the body, just behind the gill cover. This is a key identifier.

2. 2

   Lateral Stripe

   While variable, a faint to prominent dark lateral stripe may extend from the humeral spot towards the caudal peduncle. This stripe can be more pronounced in some populations or under certain conditions.

3. 3

   Body Shape

   Observe the compressed, somewhat deep body shape, typical of many Astyanax species. The overall silvery coloration is also characteristic.

4. 4

   Fin Presence

   Confirm the presence of an adipose fin, a small fleshy fin without rays located between the dorsal and caudal fins, which is a characin trait.

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