T-bar,
...nice pen...years ago, we had a place on False River, an old oxbow lake in south central LA. We had a similar "live well" attached to our pier. When we caught keeper gills and crappie, we just threw them in the well. We had them in there in many cases for a couple weeks. As long as they are not too overcrowded or the water gets too hot or stagnant, I would think they would be ok. Try a handful for a short period and go from there. I think catfish would be more stressed by the cage than sunfish. Post a pic when you're done.
