Freshwater Fishes

Redside Dace
Name: Redside Dace
Scientific Name: Clinostomus elongatus
Status: Endangered Provincially and Nationally
Details & Range Map: R.O.M.

Nearly 1,400 species of fish are found in Canadian waters; 11% of these occur in freshwater habitats. Ontario has, by far, the highest diversity of freshwater fish species of any Canadian province or territory, with a total of 154 species. This species richness is due to the large number and size of water bodies in Ontario, the mild climate, the fact that the province has two major drainage basins - the Atlantic and the Hudson Bay, and the large number of post-glacial colonization routes.


Approximately 26% of these species are of provincial conservation concern.


According to the General Status of Species in Canada (2010), six species are extirpated or extinct (Paddlefish, American Shad, Gravel Chub, Deepwater Cisco and Atlantic Salmon). A little over half (86 species) of Ontario's fish species are ranked provincially as secure. Ten species are provincially at risk (e.g., Spotted Gar, Redside Dace, Black Redhorse and Channel Darter), another three species may be at risk. Twenty-one species are sensitive (species that are not believed to be at risk of immediate extirpation or extinction but may require special attention or protection to prevent them from becoming at risk).


An incredible 20 species of Ontario's freshwater fishes are exotic. In the General Status of Species in Canada (2005), ‘exotic’ refers to species that have been moved beyond their natural range as a result of human activity. Provincially, the term invasive (or invading) species is used to describe introduced species whose introduction or spread threatens the environment, the economy or society, including human health. The presence of exotic species is one factor that threatens native freshwater fish species. Other factors that have an impact on the distribution and abundance of freshwater fishes are changes to habitat, over-fishing and pollution.


For more information on Species at Risk designations and their current status, see the Species at Risk in Ontario (SARO) List and the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) website.




W. N. Roston