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Invasive Species: Rusty Crayfish

Rusty Crayfish

(Faxonius rusticus)
*Established in Michigan waters*


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Use the Midwest Invasive Species Information Network (MISIN) online reporting tool -

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  • Lobster-like, brown body, up to 6 inches with claws.
  • Oversized claws have an oval opening when closed and black bands at tips.
  • Mature crayfish have a  dark, rusty spot on each side of the carapace.


rusty crawfish
Photo courtesy of U.S. Geological Survey

rusty closeup
Photo courtesy of Doug Watkinson Fisheries and Oceans Canada (DFO).

Habitat: Permanent water bodies (lakes, streams, wetlands) with cover of rocks, logs or trees.  Rusty crayfish do not burrow like other crayfish.

Diet:  Rusty crayfish are voracious eaters, consuming 2-3 times as much per day as native crayfish.  Rusty crayfish eat whatever is available, including plants, snails, clams, insects, other crayfish, fish eggs and small fish.

Native Range: Ohio River basin including parts of Kentucky, Ohio and Indiana.

U.S. Distribution:  Great Lakes states, New England south to North Carolina and Tennessee, western states including Colorado, Wyoming and Oregon.  Also present in Ontario, Canada.

Local Concern: Rusty crayfish destroy aquatic plant beds, affecting the fish and organisms that require this habitat.  Their broad diet can impact native populations and ecosystems.  Rusty crayfish also limit habitat and food sources used by native crayfish. 

Means of Introduction: Rusty crayfish are collected and used as bait and have been transferred by this means to many water bodies throughout Michigan and the U.S.


Rusty Crayfish Invasive Species Alert - Printable PDF

Status and Strategy for Rusty Crayfish Management This document provides in-depth information about rusty crayfish in Michigan including identification, distribution, management and control options.

Crayfish of Michigan Poster

Field Guide to Michigan Crayfish