What kind of fish is this?

[Mariah C]

There is this shale bottom river in southern Ontario (Vanderwater conservation area) that my boyfriend and I went to, and we saw these fish swimming up stream. They are long, and medium sized (not fat like a sunfish, but not super skinny either), and have grey/blue (maybe black?) bodies with bright red tails and fins. Any idea what kind of fish it is? We're pretty curious ,