Hey Larry,
I use an aerator that's just a bilge pump motor with a special base that has a piece of tubing coming from the outside of the bait tank (I use a big ice chest) that draws in air and mixes it into the water as it circulates the water in the livewell. Its made by Keep Alive and called an Oxygen Infuser. Here’s a link - Keep Alive
Its on a timer (bought separately) that runs it for 30 seconds at a time and you can adjust the time between runs - I usually have it run every 2 to 5 minutes depending on how hot the weather is and how many minnows I have.
It runs this way 24/7 year around and the first one I had lasted over two years. When it went bad I just replaced the motor with a bilge pump motor that was a lot cheaper than buying the whole thing with the special base.
I keep minnows for weeks at a time and loose very few. I replace the water with 58-degree well water twice a day except in the winter when once a day is enough. In hot weather I add ice or ice water to the tank if I’m out all day.
Hope this helps,