Fishhook waterflea (Cercopagis pengoi)

Fishhook waterflea map
Image by USGS

Map of fishhook waterflea (Cercopagis pengoi) in the United States

Fishhook Waterflea

Fishhook waterflea ( Cercopagis pengoi), known in North America as the “fishhook water flea,” is an aggressive, predatory zooplankton that preys on smaller zooplankton. Since its first discovery in Lake Ontario in August 1998, copagis spread inland to six of New York’s Finger Lakes (Seneca, Cayuga, Otisco, Canandaigua, Owasco and Keuka) within a year, possibly on fishery sampling gear, in bait buckets, or on recreational angling equipment. In these inland lakes, Cercopagis now dominates the offshore zooplankton community during the summer and fall [from NY Invasive Species Clearinghouse].


Fishhook waterflea on the New York Invasive Species Clearinghouse website covers identification and mapping of the waterflea.

Waterflea Dispersal - a research paper on "Fouling of fishing line by waterflea Cercopagis pengoi: a mechanism of human-mediated dispersal of zooplankton?" 

Fishhook waterflea Factsheet on the U.S. Geological Survey website covers covers identification, nonindigenous occurrences, ecology, and management of the species.

Last updated September 15, 2023