It is one of a few meromictic lakes in Ontario, that is, its deep bottom waters (21 metres or 70 feet) are totally devoid of oxygen.

[2] Restrictions on lake use include no motorized boats, no fertilizer or pesticide use, and regular septic tank inspections.

The Sunfish Lake Association has been instrumental in engaging the media and the community in the Region of Waterloo's Environmentally Sensitive Lands initiative, which is similar to a local greenway.

The association members have also been supportive of Ontario Nature's greenway initiative, and regularly share their experiences with engaging landowners and the broader community.

The group owns and stewards 50 acres (200,000 m2) of woodland and wetland surrounding Sunfish Lake.