American Flagfish Identification Guide
Recognize the American flagfish by its deep body, red-spotted rows, and the dark eyespot blotch below a male's dorsal fin.
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Key identification features
- Deep-bodied, compact, and robust shape compared to slimmer killifish
- Males show blue-green iridescent scales overlaid with rows of red-orange spots
- Prominent dark ocellus (eyespot) blotch just below and behind the dorsal fin in males
- Rounded dorsal and anal fins, no elongated fin extensions
- Females and juveniles are duller olive-tan with a single dark spot near the caudal peduncle
- Maximum size around 2.5 inches
Common look-alikes
- Sheepshead minnow: shows clean vertical bars rather than rows of spots, and lacks the dark ocellus blotch
- Other Fundulus topminnows: generally slimmer-bodied and lack both the eyespot and the deep, laterally compressed profile
- Male guppies: superficially colorful but have a rounded, fan-shaped tail and lack the flagfish's deep body and eyespot
Where you'll see one
The American flagfish is native to peninsular Florida and parts of the southeastern United States. It favors quiet, well-vegetated habitats such as ponds, ditches, spring runs, and slow-moving streams, often grazing on algae along plants and submerged surfaces.
Frequently asked questions
How do I sex an American flagfish by sight?
Males show bright blue-green iridescence, rows of red spots, and a dark ocellus blotch below the dorsal fin, while females are duller olive-tan with only a small dark spot near the tail.
How is the flagfish different from the sheepshead minnow, which shares similar habitat?
The flagfish has rows of red spots and a dark eyespot patch, while the sheepshead minnow instead shows distinct dark vertical bars down a deeper, more laterally flattened body.