Bigmouth Buffalo
Ictiobus cyprinellus By Zachary R. Shattuck

This story is featured in Montana Outdoors May-June 2018 issue

I first encountered the mighty bigmouth buffalo—the largest of all the sucker species—by chance. While snagging for paddlefish in a sluggish pool of the Missouri River upstream from Fort Peck Reservoir, I thought I’d tied into a whopper “spoonbill” and was about to fill my tag. The big fish turned out to be a powerful “buff” of about 15 pounds. While it wasn’t the fish I was after, I was excited to have the opportunity to appreciate the size and beauty of one of Montana’s largest fish—a native species many people don’t even know exists.

The bigmouth buffalo is commonly confused with the native smallmouth buffalo (a fellow member of the sucker, or Catostomidae, family) and the introduced common carp (a member of the minnow, or Cyprinidae, family). All three are large fish with big scales. But the bigmouth buffalo has a mouth at the front of the head, much like a trout’s, while the smallmouth buffalo and common carp have mouths angled downward like most other sucker species. Also, the common carp has two barbels (whiskerlike projections) on either side of the upper jaw and leading serrated “spines” along the dorsal and anal fins. Buffalo fish have no barbels and soft fin rays.

The bigmouth buffalo has a bluish-green or coppery back, fading to lighter sides. Its body is deeply rounded, as is the head. This is a big fish; in Midwestern states it can weigh more than 80 pounds. In Montana, biologists commonly net specimens over 25 pounds. The state record, caught in Nelson Reservoir, weighed 47.75 pounds and was 40.7 inches long.

Range and habitat
In North America, the bigmouth buffalo ranges from Montana east through the Great Lakes states and from Saskatchewan south through Louisiana. As with the shortnose gar and smallmouth buffalo, the bigmouth buffalo’s range in Montana is the species’ westernmost extent. Like the smallmouth buffalo, the bigmouth lives in the Yellowstone, Missouri, and lower Milk Rivers as well as in impoundments, including Fort Peck and Nelson Reservoirs. While numerous other large-river fish fared poorly after their riverine habitat was impounded by dams, bigmouth buffalo have flourished with the newfound abundance of still water and plentiful zooplankton.

Bigmouth buffalo typically prefer warm water rich in algae and zooplankton, which the fish collect with fine, comblike gill rakers. Unlike most other sucker species, which feed mainly on a river or lake bottom, bigmouth buffalo feed throughout the water column.

Bigmouth buffalo gather to spawn in May through June along vegetated lake margins and flooded backwaters, or in small tributaries. After several males surround a female, she sinks to the bottom to deposit her eggs over submerged vegetation. “All at once, the fish rush forward 15 to 20 feet, churning the water into foam with their tails in a spectacular display called ‘tumbling,’ which mixes the eggs and milt,” notes The Great Minnesota Fish Book. (Would such a spectacle be considered an aquatic “buffalo stampede”?)

Angling and food value
Owing to their preferred diet of zooplankton, bigmouth buffalo are difficult to catch. Anglers occasionally hook one using small pieces of nightcrawler, small doughballs, or corn kernels. Suckers are generally not sought for their meat because the flesh, while delicious, is filled with bones. But because bigmouth buffalo are so large, their bones can be easily eaten around, especially when the fish are smoked and the meat becomes flakey. Millions of pounds of bigmouth buffalo are commercially harvested in the Midwestern stretches of the Missouri and Mississippi Rivers each year and sold in markets throughout the eastern half of the United States.Bear bullet

Zachary R. Shattuck is a native fish species coordinator for FWP..