The Enos Lake stickleback is restricted to a small lake on Vancouver Island, British Columbia. The lake has highly productive benthic and pelagic layers. The climate in the area is hot and dry in summer and cool and wet in winter.

The benthic Enos Lake stickleback has adapted in many ways to equip itself for life close to the lake floor. For example, the benthic fish has evolved smaller eyes and a shorter jaw than its limnetic sister.

The limnetic Enos Lake stickleback has adapted in many ways to equip itself for life close to the water's surface. For example, the fish has evolved longer gill rakers than its benthic sister.