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Montana Field Guide

Montana Field Guides

Bigmouth Buffalo - Ictiobus cyprinellus

Native/Non-native Species
(depends on location or taxa)

Global Rank: G5
State Rank: S4

Agency Status

External Links

General Description
The Bigmouth Buffalo has a more terminal mouth, (that is, opening at the front of the head), which allows it to feed on plankton as well as bottom organisms and detritus. These barrel-shaped fish are rarely taken on hook and line. Bigmouth Buffalo can produce hundreds of thousands of eggs and live over 20 years.

Diagnostic Characteristics
Usually dark colored (brownish or blackish), often with a coppery sheen; sometimes greenish or gray. Underside whitish or yellow; fins dark.

Species Range
Montana Range Range Descriptions

All Ranges
(Click legend blocks to view individual ranges)

Western Hemisphere Range


Observations in Montana Natural Heritage Program Database
Number of Observations: 410

(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)

Make long spawning movements from lower Missouri River to upstream areas. Dispersal downstream follows.

Large rivers and reservoirs. Spawn in larger streams with backwater areas.

Food Habits
Plankton, crustaceans, and diptera larvae are the major food items.

Downstream portions of Yellowstone River important as rearing areas. Adults school.

Reproductive Characteristics
Can reach 112 years of age (Lackmann et al. 2019). Spawns May - July at 60 degrees F. in shallow water. Sexual mature at 3 yrs. Spawns over bottom or on vegetation. Incubation: 8 - 14 days. Spawn peaks early to mid June on middle Missouri River.

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Citation for data on this website:
Bigmouth Buffalo — Ictiobus cyprinellus.  Montana Field Guide.  .  Retrieved on , from