Winter Oxygen test: Get yourself a few dozen FH and leave them in the bait bucket (lid on) without changing water for about three days. Wait until they are all up close to the surface of the water in the bucket. Now drill a hole in the ice, dump the minnow bucket water out on the ice and fill the bucket with water from the hole you just bored. Weight 10 minutes. If the FH have all moved to the bottom of the bucket and are congregated together the oxygen level in your pond water is good. Natures own tools at work.
