How to Identify Eel

To identify Eel (Anguilla), look at these key features.

Physical Characteristics

Body shape

eel-like

Coloration

Highly variable depending on life stage and species. 'Yellow eels' (juvenile/adult freshwater stage) typically have yellowish-brown to olive-green backs and yellowish-white bellies. 'Silver eels' (migratory stage) develop a silvery-white belly and darker, often blackish, backs, with enlarged eyes. Glass eels are transparent.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Elongated, snake-like body, Small, embedded scales (often not visible to the naked eye), Continuous dorsal, caudal, and anal fins forming a single fringe around the posterior body, Small, rounded pectoral fins, Absence of pelvic fins, Small, slit-like gill openings located just in front of the pectoral fins, Protruding lower jaw (prognathous)

Dorsal fin

Long, continuous, originating far behind the pectoral fins and merging with the caudal and anal fins.

Tail fin

Rounded, confluent with dorsal and anal fins.

Pectoral fin

Small, rounded, located just behind the gill openings.

Distinctive fins

Absence of pelvic fins; dorsal, caudal, and anal fins form a single, continuous fin fold.

Identification Tips

1. 1

   Body Shape

   Look for the characteristic elongated, snake-like body. This immediately distinguishes them from most other fish.

2. 2

   Fin Structure

   Observe the continuous dorsal, caudal, and anal fins that form a single fringe. The absence of pelvic fins is also a key identifier.

3. 3

   Gill Openings

   Note the small, slit-like gill openings located just in front of the pectoral fins, rather than large opercula.

4. 4

   Scales

   While present, the scales are very small and embedded in the skin, making the body appear smooth and scaleless to the touch.

5. 5

   Life Stage Coloration

   Distinguish between 'yellow eels' (freshwater, yellowish-brown) and 'silver eels' (migratory, silvery belly, darker back, enlarged eyes). Glass eels are transparent.

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