How to Identify Spiny Eel

To identify Spiny Eel (Macrognathus aculeatus), look at these key features.

Physical Characteristics

Body shape

eel-like

Coloration

The body is typically light brown to olive-brown, often with a series of irregular dark spots or stripes along the flanks. A distinctive row of ocelli (eye-spots) or dark blotches, often ringed with yellow or orange, runs along the base of the soft dorsal fin. The ventral side is usually lighter.

Scale type

cycloid

Mouth position

superior

Distinctive features

Elongated, snake-like body, Pointed, fleshy snout with a trilobed appendage at the tip, Small, isolated dorsal fin spines (20-35) preceding the soft dorsal fin, A series of ocelli or dark blotches along the dorsal fin base, Small, embedded scales

Dorsal fin

Composed of 20-35 isolated, sharp spines followed by a soft-rayed portion (44-55 soft rays) that is confluent with the caudal fin.

Tail fin

Rounded to slightly spatulate, confluent with the dorsal and anal fins.

Pectoral fin

Small and rounded, typically with 20-25 rays.

Distinctive fins

Anal fin (44-55 soft rays) is also confluent with the caudal fin, similar to the dorsal fin. Pelvic fins are absent.

Identification Tips

1. 1

   Body Shape

   Look for the distinctly elongated, eel-like body, which is laterally compressed.

2. 2

   Snout

   Observe the pointed, fleshy snout with a characteristic trilobed appendage at its tip, used for probing in substrate.

3. 3

   Dorsal Fin Spines

   Count the series of small, isolated, sharp spines (20-35) along the back, anterior to the soft dorsal fin. These are a key diagnostic feature.

4. 4

   Coloration and Pattern

   Note the brown to olive body color with irregular dark markings and the row of ocelli or dark blotches along the base of the soft dorsal fin.

5. 5

   Fin Confluence

   The dorsal, caudal, and anal fins are typically confluent, forming a continuous fin structure around the posterior part of the body.

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