What’s Swimming Through the Shallows?

We stocked the pond at Nature Boardwalk at Lincoln Park Zoo with fish in July, and we’re already seeing successful reproduction! Bluegill, pumpkinseed and fathead minnows have all produced fry (baby fish).

Fish fry in the waters of Nature Boardwalk.

To see these fish—the first generation since the pond’s transformation—look in shallow areas with some shade. The fish are often seen congregating in the shadows of submerged objects such as rocks or branches.

The landscape of Nature Boardwalk was designed with wildlife in mind, including fish. The pond is now about 20 feet deep in the deepest sections, which will protect the fish from winter freezing. There are also aerators throughout the pond to keep dissolved oxygen levels high—an important water-quality parameter for fish.

A fry is tallied in a petri dish before being returned to the pond.

For fish to reproduce and create self-sustaining populations, you need shallow sandy or gravelly areas for fish to spawn. For prey fish, we also added submerged objects like tree branches or logs. These objects provide cover so the fish will feel safe enough to reproduce. We are happy to see all of the fry; these landscape design features seem to be working!

Vicky Hunt


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