The zoo has a large aquarium set up to house a collection of native fish that can be found in the lakes and rivers of Wisconsin. Perch and bluegill are the two species of fish the zoo has right now. The perch can be recognized by its distinctive stripes, while the bluegill has a blue or black "ear" which is actually an extension of its gill cover.
- Bony fish have a gas filled bladder, which is used to adjust their buoyancy and is covered in overlapping flexible scales.
- Swimming muscles anchor the long extensions of a fish's vertebrae.
- Fish are cold blooded and their body temperature is tied to the water around them. Some fish will move to different depths of a lake or pond to stay at their optimal body temperature as the seasons change.
There is no loss in the perch or bluegill populations due to the management and stocking of lakes and ponds for commercial and sport fishermen.
Threats for fish populations include being eaten by predator fish and changes to their habitat.