The Redear Sunfish is a popular choice for pond stockings because it can grow to a large size, it tends not to overpopulate, and it eats snails, which are the intermediate host of several fish parasites. However, Wisconsin DNR will not allow Redear stockings, and severe winters in the upper Midwest may kill them in certain water bodies.
Redear Sunfish Advice:
We generally recommend only stocking this species in ponds and lakes that have deeper basins that will prevent extremely cold winter water temperatures, which commonly occur in small shallow ponds. Also, Redear Sunfish tend to do best in water bodies with vegetated shorelines and clear water (probably because this is preferred environment for its primary food sources: insect larvae & snails).
When stocking to control snails, we have typically introduced as many as 500 per surface acre in the spring. When stocking to add diversity to a water-body, 100 per surface acre is a more typical amount