How to Identify Tessellated Darter

To identify Tessellated Darter (Etheostoma olmstedi), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Cryptic, mottled pattern of brown, olive, and black on a lighter tan or yellowish background. Distinctive W- or X-shaped markings along the lateral line. Ventral surface is typically lighter. Breeding males may exhibit more intense coloration, sometimes with iridescent blue or green hues on the fins and body.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

W- or X-shaped markings along the flanks, Two dorsal fins, the first spiny and the second soft-rayed, Small, slender body adapted for benthic life, Lack of a swim bladder (or greatly reduced)

Dorsal fin

Two dorsal fins; the first with 8-12 spines, the second with 10-14 soft rays. The two fins are typically separate or barely connected.

Tail fin

Slightly emarginate to truncate caudal fin.

Pectoral fin

Large, fan-like pectoral fins, typically with 12-15 rays, used for propping on the substrate.

Distinctive fins

Pelvic fins are thoracic in position, located directly below or slightly anterior to the pectoral fins. Anal fin has 2 spines and 7-10 soft rays.

Identification Tips

1. 1

   Body Markings

   Look for the characteristic W- or X-shaped dark markings along the sides, which are often interconnected, forming a tessellated pattern.

2. 2

   Dorsal Fins

   Observe the two distinct dorsal fins; the first is spiny, and the second is soft-rayed. They are usually separate or only narrowly joined.

3. 3

   Size and Shape

   Small, slender, and elongated body, typical of darters, adapted for bottom dwelling.

4. 4

   Substrate Preference

   Often found resting on the bottom, darting short distances when disturbed, rather than swimming freely in the water column.

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