Stop the Spread-Spiny Water Flea

Stop the Spread-Spiny Water Flea

Trout Unlimited Canada’s Stop the Spread campaign focuses on preventing the spread and impact of invasive species and pathogens that threaten Canada’s fisheries.  There are a number of invasive species threatening Canada’s water. Meet the Spiny Water Flea.

The Spiny Water Flea was first introduced to North American waters from the ballast tanks from merchant ships traveling into our waters from Europe and Asia.


spiny-water-fleaSpiny Water Flea is currently found in the Great Lakes.  Ranging in size from approximately 8 to 12 mm including the tail, these fresh-water crustaceans are native to northern Europe and Asia. The head of the spiny water flea consists primarily of a large black eye that is well defined from its abdomen, which has four pairs of legs. Its tail is barbed (with 1 to 3 pairs of barbs) and is twice as long as its body.  The barbed tail acts as an effective deterrent to small fish trying to feed on them. Asexually produced fleas have a kink in the middle of their spine whereas sexually produced fleas do not.

Impact of Spiny Water Flea to Our Environment

The Spiny Water Flea is capable of asexual production, resulting in population explosions. Sexual production increases their genetic variability and their ability to survive and disperse under adverse environmental conditions and a wide range of water temperatures.

Sexually produced eggs can go into a semi-static dormant metabolic condition and can over-winter and hatch when temperatures exceed 4oC. In addition, dormant eggs can survive passage through fish digestive tracts.

Why Should We Care?

  • Spiny water fleas disrupt the biodiversity of lakes they invade by out competing and consuming large numbers of the native zooplankton,creating an imbalance that ripples throughout the entire food chain.
  • Although capable of  sexual reproduction, most spiny water fleas reproduce asexually.  A single female alone can quickly colonize new habitat pushing out and negatively impacting native species.
  • Spiny water fleas reduce the available food for our native fish and they are mostly non-digestible or palatable to larger fish.
  • Large numbers of spiny water fleas gather together forming a jelly mass that clogs fishing gear and other equipment.

How Can You Stop the Spread?

There are four primary ways you can stop the spread of Spiny Water Flea

  1. Boating and fishing equipment should be cleaned with hot (140 C) high-pressure water and allowed to dry for at least five days prior to transporting to another waterbody, but longer periods are recommended.
  2. If you are using bait, bait buckets should always be emptied on land, far from water bodies.
  3. Talk and inform others about the dangers of Spiny Water Flea and other aquatic invasives.
  4. Support Trout Unlimited Canada’s Stop the Spread program.