Rainbow Smelt

Rainbow Smelt (RWS)

Where are RWS from and how did they get here?
RWS are an anadromous species (naturally living in salt water, and moving to freshwater to spawn) native to the East Coast near New Jersey. They were stocked into a Michigan lake to act as a “feeder fish” for larger fish species, and spread from there via connecting waterways.

How do I identify RWS?
RWS have slender and cylindrical body shapes. They are silvery, and some say they smell of cucumbers when fresh and still alive. They have an anal fin and an adipose fin, and a deeply forked tail. They have visible teeth when their mouth is open
Please contact our Water Program Coordinator if you think you have found RWS.

RWS- note the fins and long slender body

RWS have visible, sharp teeth when their mouths are open

How do RWS affect Wisconsin water bodies?
RWS cause declines in native fisheries, especially in yellow perch and ciscos. They compete for food sources, and also prey on young-of-year fish.

What can be done once RWS enter a water body?
Little can be done to remove a RWS population once it establishes in a water body. The best treatment is to prevent them from establishing in the first place. It is important to drain all water from boats before leaving landings, and to never dump bait buckets into lakes.