I live in central Indiana and it gets pretty cold in winter. I am able to get an alligator gar because they used to likve in Kentucky before they were killed all the way down to Florida. I am going to keep natives. My pond is 12x7x3 with a 2x1 shelf in one corner that is 1.5 feet deep. It is a little bit over 1000 gallons. It has an over adequate biological filter that serves as the mechanical. I was thinking of stocking it with pike or 2 tiger muskies. here will be a clean up crew of blue gill of about 4-5 inches for sure, What fish should I keep in it in replace of or with the esox?