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Montana Field Guide

Montana Field Guides

Northern Plains Killifish - Fundulus kansae

Non-native Species

Global Rank: G5
State Rank: SNA

Agency Status


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General Description
The plains killifish has probably been introduced into Montana's eastern drainage. This fish has an unusual appearance for a Montana fish because it bears vertical stripes. It typically inhabits small, low-gradient streams and spawns in the spring by broadcasting its eggs. The plains killifish eats primarily insects and other invertebrates that are taken largely from the surface of the water by its mouth, which is located near the top of its head. Hence, the common name of topminnow. The largest size of this killifish is about 6 inches.

Diagnostic Characteristics
Olive brown on back, fading to pale yellow or white below. Side has 12 to 28 dark vertical bars (bars, on female are narrower and more numerous, as in illustration). Head broad and flat, lateral line absent.

Species Range
Montana Range


Western Hemisphere Range


Observations in Montana Natural Heritage Program Database
Number of Observations: 319

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Found in small clear water creeks where substrate is mostly of a silt-clay type. Alkalinity and salinity may be a factor in stream selection.

Food Habits
Feed effectively at all levels and food habits are generalized. Prefer aquatic insects but also feed on plants.

Spend most of their in loosely organized schools. Has now been found in 19 streams in the Yellowstone Basin.

Reproductive Characteristics
Spawns April-August when water temperatures reach 80 degrees F. Mate after brief courtship. Sexually mature at 2 years.

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Citation for data on this website:
Northern Plains Killifish — Fundulus kansae.  Montana Field Guide.  .  Retrieved on , from