From the Wisc DNR site....
"Using Fish as Bait"
Fish other than minnows may be used as bait. Typically, bluegills and perch are used in this fashion. However, if there is a minimum length limit for the bait fish on that water, it still applies. For example, if there is an 8 inch minimum length limit on perch in the lake, the perch you are using for bait would have to be 8 inches or greater in length. Only fish caught in that water can be used as bait on that water, unless they are dead and have been preserved by a method that does not require refrigeration or freezing. Live game or rough fish cannot be moved away from a water, with a few very limited exceptions.
Also keep in mind that any fish that are caught and used as bait must be counted towards your daily bag limit. For example, you can only keep 25 panfish on most inland lakes, including any that were used as bait. Any fish that is not released immediately must be counted toward your daily bag limit, even if you later release it or lose it to a bigger fish.
For exceptions to the 25 panfish limit, please see the current hook and line regulations.
Also from Wisc dnr site ...specifically regarding Lake Geneva...
"Geneva Lake: The minimum length limit on northern pike is 32" with a daily bag limit of 1."
Looks to me like you're good to go 
Unless they changed something=)
