"Temperatures for goldfish are a surprisingly complex issue. Goldfish are technically cold-water fish. However, just because goldfish can survive a wide range of temperatures does not mean they are healthy or happy at those temperatures.
Goldfish in the wild, so to speak, can survive temperature ranges of forty to one hundred six degrees. The extremes will kill goldfish if the exposure lasts for long.
The optimum temperature range is sixty-eight to seventy-five degrees. Some breeds prefer slightly warmer temperatures.
Sudden changes of temperatures can be fatal, even within the ranges given above. While the classic method to deal with this is to spend twenty minutes or so of slow immersion time to equalize the temperatures. For extreme situations such as purchasing a goldfish in a store at seventy degrees to place in a pond when the outdoors temperature is forty, it may take days or weeks of careful preparation to avoid a high chance of death. "
"While goldfish don't like temperatures over 75°F (24°C), they do seem to like seasonal variations where the temperature falls to the high 50s or 60s (15-20°c) in the winter. Fancier goldfish are an exception and cannot easily tolerate temperatures below about 60°F (16°c)."
We are not talking about common goldfish. We are talking about Oranda and fantail goldfish. These goldfish perfer thier water temp to not drop below 60 f nor above 75 f. Seening how this persons water is 71 then this persons water is just fine for fanny goldfish. Not all goldfish do well in the cold temp waters that you say they do.