Mom had a pond, a pier with 55 gal plastic barrels as floats under it. I made a box with 1/8" hardware cloth, 12" wide, 24" long, 36" deep. First it was tied to the side, heat would kill the minnows. I cut a hole in the center with a cover, that was better. The pier was on the northeast side of the pond. We moved it to the southeast side and minnows would live longer.