Contact information
For information on Lakes in Wisconsin, contact:
Division of Water
Bureau of Water Quality
Aquatic Invasive Species Contacts

Spiny Waterflea - Trout Lake

Date First Found
Location First Found
Trout Lake deep hole

About Spiny Waterfleas

Both waterfleas entered the Great Lakes in ship ballast water from Europe – the spiny waterflea arrived in the 1980’s, followed in the 1990’s by the fishhook water flea. Only about ¼ to ½ inches in length, individual waterfleas may go unnoticed. However, both species tend to gather in masses on fishing lines and downrigger cables, so anglers may be the first to discover a new infestation. Spiny and fishhook waterfleas are predators - they eat smaller zooplankton (planktonic animals), including Daphnia. This puts them in direct competition with juvenile fish for food. Young fish have trouble eating these waterfleas due to their long, spiny tails. The spiny and fishhook water fleas produce rapidly through parthenogenesis, commonly known as asexual reproduction, which means that no males are required and populations can explode in number.