in a fishing boat , a built - in tank which serves the combined function of a livewell for holding fish that are caught and a bait well for receiving a minnow bucket . an electric pump powered by the battery of the boat pumps water from the lake into the tank in a manner to aerate the water and circulate it in the tank . a drain tube drains off water from the tank and prevents overflow . one half of the tank serves as a bait well in which a minnow bucket may be suspended . the other half of the tank is a livewell which receives newly caught fish . the livewell and bait well have separate hinged lids .