How to Identify Striped Killifish

To identify Striped Killifish (Fundulus majalis), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Males typically exhibit 15-20 dark, vertical bars on their sides, often with iridescent blue or green hues, especially during breeding season. Females have 10-12 dark, horizontal stripes or rows of spots along their sides. Both sexes have a pale belly. Coloration can vary with habitat and mood.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Sexual dimorphism in striping pattern (vertical bars in males, horizontal stripes/spots in females), Relatively large, flattened head, Terminal mouth with small, conical teeth, Robust body

Dorsal fin

Single dorsal fin, located posteriorly, with 10-13 soft rays. Origin is typically posterior to the anal fin origin.

Tail fin

Rounded to slightly emarginate caudal fin.

Pectoral fin

Moderately sized pectoral fins.

Distinctive fins

Anal fin with 10-12 soft rays, similar in shape to the dorsal fin. Pelvic fins are small and abdominal.

Identification Tips

1. 1

   Body Pattern (Males)

   Look for prominent dark, vertical bars (15-20) on the sides, especially noticeable during breeding season when colors are more vibrant.

2. 2

   Body Pattern (Females)

   Observe 10-12 dark, horizontal stripes or rows of spots along the sides, which is a key differentiator from males.

3. 3

   Head Shape

   Note the relatively large and somewhat flattened head, characteristic of the genus Fundulus.

4. 4

   Mouth Position

   The mouth is terminal (at the very front of the head), indicating its surface-feeding habits.

5. 5

   Habitat

   Presence in shallow, brackish to marine estuarine environments is a strong indicator.

Explore Striped Killifish