How to Identify Johnny Darter

To identify Johnny Darter (Etheostoma nigrum), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Generally light tan to yellowish-brown dorsally, fading to a lighter ventral surface. The most distinctive feature is a series of 6-10 dark, W- or X-shaped markings along the lateral line. Fins are typically clear to slightly dusky, often with faint banding. Breeding males become darker, sometimes nearly black, with intensified markings and often develop tubercles on their fins and body.

Scale type

ctenoid

Mouth position

subterminal

Distinctive features

Slender, cylindrical body, Two dorsal fins, distinctly separated, W- or X-shaped markings along the lateral line, Small, subterminal mouth, Absence of a frenum (a fleshy bridge connecting the upper lip to the snout)

Dorsal fin

Two dorsal fins; the first spiny (7-11 spines), the second soft-rayed (10-14 rays). The two fins are distinctly separated.

Tail fin

Caudal fin is slightly emarginate to truncate.

Pectoral fin

Pectoral fins are relatively large and fan-shaped, with 12-15 rays.

Distinctive fins

Pelvic fins are thoracic, located beneath the pectoral fins, and have one spine and five rays. Anal fin has 2 spines and 7-10 rays.

Identification Tips

1. 1

   Lateral Markings

   Look for the characteristic 6-10 dark, W- or X-shaped markings along the sides of the body. This is the most reliable field mark.

2. 2

   Dorsal Fins

   Note the two distinctly separated dorsal fins. Many other darter species have them closer together or continuous.

3. 3

   Snout and Mouth

   The snout is blunt, and the mouth is small and subterminal. Crucially, there is no fleshy frenum connecting the upper lip to the snout, allowing the upper lip to be protruded.

4. 4

   Body Shape

   Its body is relatively slender and cylindrical, not as compressed as some other darter species.

5. 5

   Absence of Preopercular Spines

   Unlike some other darter genera, Etheostoma nigrum lacks a distinct spine on the preopercle (bone below the eye).

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