Cold tolerance

[Virginia ranchu]

January's cold snap on the East coast was the worst in several years. My pond de-icer failed...it got stuck in the ice, but the aerator was on, and maintained a hole in the ice. I was worried that my ranchu might not make it out alive. I waited for a natural warm up and checked the fish over. I noticed that the oldest fish didn't do so well. I have a few ranchu that are 5+ years old, and two of them had dropsy. The three year old fish had "bed sores" where they had been resting on the bottom. Only the < 2year old fish looked unharmed.

I brought the dropsied fish indoors and put them in a clean tank with a filter and did not feed for three days. I started them back with bloodworms and gel food. I used no medication, and they recovered. I am pretty sure that they would have died before spring if I had left them outside.

I also brought in some breeders in the hope of some spawnings in February. These fish have some red sores on their undersides, but don't look too bad.

For the fish that are still outside, I am wondering if I should invest in a new pond de-icer, or just keep using aeration? I am not sure if a pond de-icer is supposed to actually raise the pond temperature, or if it just maintains an ice free zone for gas exchange. If that is the case, the air pump does the same thing.

thanks,

Rob

[BruceP]

Air pump does the same thing. Electric de-icer just keeps a hole open. There isnt enough wattage to actually heat the water.

[bekko]

I think the thermostat in the de-icer is set for 42F which is the magical temperature of maximum density for fresh water.

-steve