How to Identify Alevin

To identify Alevin (Variable selon l'espèce), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Translucent to pale, with visible internal organs and a prominent yellowish yolk sac attached to the ventral side.

Scale type

none

Mouth position

terminal

Distinctive features

Large, visible yolk sac attached to the ventral surface, Rudimentary fins, often not fully developed or functional for swimming, Lack of scales, Often possess a 'pro-larval' appearance with undeveloped features

Dorsal fin

Often present as a low fin fold or rudimentary structure, not fully rayed.

Tail fin

Caudal fin typically present as a fin fold, not fully forked or developed.

Pectoral fin

Small, paddle-like, or rudimentary, used for stability rather than propulsion.

Distinctive fins

Adipose fin may be present in species like salmonids, but is small and undeveloped.

Identification Tips

1. 1

   Yolk Sac

   The most defining characteristic is the prominent, spherical to ovoid yolk sac attached to the ventral side, providing nourishment. Its size decreases as the alevin develops.

2. 2

   Size

   Typically very small, ranging from a few millimeters to 2-3 cm, depending on the species and developmental stage.

3. 3

   Coloration

   Generally translucent or pale, allowing internal organs and the developing spine to be visible. Pigmentation is minimal.

4. 4

   Behavior

   Largely immobile, remaining hidden within gravel. Limited swimming ability, primarily for short bursts or maintaining position.

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