I have a new problem and I am hoping you can help. Many of my fish are 'swimming' up to the hole in the ice which the heater has kept open all winter. I'm not sure what is happening. Any ideas???

Three things come to mind right away.

1) Your hole in the ice is the warmest water in the pond, and the fish will stay close to it if they can. For proof of that, you just need to look at the Bateman's pond in early spring. Their pond heater serves a small but fast "creek" which empties into a corner of the pond next to the deck. It provides a constant supply of warm water and a constant show of big koi impersonating salmon swimming upstream. Silly.

2) Unless you have an airstone somewhere under the ice (which you should, about 1 foot below the surface), that hole has the highest concentration of oxygen in your pond right now. Your fish may be seeking breathable water. If you do not have an airstone running shallow now, get one in as soon as you can.

By the way, did you clean out your pond last fall? If there is any amount of plant debris or sludge on the bottom, it's producing noxious gas right now due to anaerobic breakdown, and the hole in the ice is the least nasty part of the pond.

(Answer courtesy Bob Passovoy)