Question
Hi, Robyn.  We have an earth embankment pond 67 x 112 feet, 6 feet deep in
the center, here in North Idaho.  This summer I put about 70 comets in the
pond for the turtles, figuring they had a better chance there than in the tank
at the pet store....  We now have hundreds of dark comets of all sizes, and the
original orange ones have grown to 4-5 inches long.  We don't feed them.  
Last winter the ice froze to about 5-6 inches thick.  The pond is spring-fed
year round.  While I hear that goldfish can handle cold water, or even freeze,
does there need to be a hole in the ice for gas exchange for fish in a pond
this size?  If so, do you know of any solar de-icers, as there is no electrical
outlet within 200 feet.  Thank you!  --Connie

Answer
The dark comets will change colors as they grow larger, eventually looking similar to the parents.  Your comets will easily grow to 14" in that size pond in just a few years.

Goldfish cannot survive being frozen solid; they'll die.  Your pond is deep enough that they won't freeze solid in your pond and can overwinter.  Your pond is also large enough that they should survive without a de-icer which would have a minute impact on a pond that large anyway.  Aerating the pond, even in the winter, is a good idea.  There are companies catering to larger ponds that sell pond aerators.  Aerators keep a hole in the ice for all but the coldest days of the year.  Most are electric but they have some that are run by windmill power.  My farm pond page at http://www.fishpondinfo.com/farm.htm has some links to companies catering to larger ponds.

There are no actual de-icers that work without electricity.  You can however keep a hole in the ice longer than natural just by floating things in the pond such as something large and black to absorb heat.  Anything non-toxic that the animals can't get in trouble with should work. My winterizing page has some ideas that don't require electricity.  See http://www.fishpondinfo.com/winter.htm

Good luck!