Carp and Mosquitofish are problem fish in Whitehorse.

Carp are an introduced species which have affected the ecosystems of many of our waterways including Blackburn Lake. Carp contribute greatly to the turbidity of the lake water as they are "bottom-feeders", rifling through the muddy lake floor uprooting water plants and decreasing light and oxygen levels.

Mosquitofish are also prevalent in Blackburn Lake. These are the small (4 to 6cm) grey/spotted black fish seen in the Lake. They are also an introduced species (from the USA) spread around the world for mosquito control. Unfortunately the voracious meat eaters eat anything - tadpoles and native insects too, making them a major threat to our native species.