How to Identify Pygmy Killifish

To identify Pygmy Killifish (Leptolucania ommata), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Males are generally more colorful, displaying iridescent olive-brown to reddish-brown bodies with faint vertical bars and often a reddish or orange tint on the fins. Females are typically duller, olive-brown to tan, with a prominent black ocellus (eye-spot) ringed in gold or white on the posterior part of the dorsal fin. Both sexes have a dark lateral stripe that may be broken into spots.

Scale type

cycloid

Mouth position

superior

Distinctive features

Smallest killifish in North America, Prominent ocellus on female dorsal fin, Slender, somewhat compressed body, Upward-pointing mouth

Dorsal fin

Small, set far back on the body, originating posterior to the anal fin origin. Females have a distinct ocellus.

Tail fin

Rounded to slightly truncate.

Pectoral fin

Small and rounded.

Distinctive fins

All fins are relatively small and rounded, proportional to their diminutive body size.

Identification Tips

1. 1

   Size

   Its extremely small size (typically under 3 cm) is a primary identifier.

2. 2

   Female Dorsal Ocellus

   The distinct black, white-ringed spot on the dorsal fin of females is a key diagnostic feature.

3. 3

   Body Shape and Coloration

   Slender body, olive-brown to reddish hues in males, and the presence of a lateral stripe or series of spots.

4. 4

   Habitat

   Presence in heavily vegetated, slow-moving, often acidic waters of the southeastern US coastal plain.

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