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Originally Posted by tkfury  Ah, that I wasn't aware about, sorry. Do you mean something like seasonal tempature changes (I've heard a lot of people keep goldfish in ponds in my area but never gave it any thought). |
Nothing to be sorry about. The current term is "temperate water", basically meaning "constantly changing". The old term was "cool water" or "cold water", which meant the same thing, but could easily be interpreted differently.
Yes, carp (the ancestors of goldfish) live in streams and lakes that are subjected to seasonal temperature changes. The reason that I make the point of saying that they don't necessarily need cold water is that a goldfish is actually more capable of dealing with 85+ degree water than most tropical fish. It can only do so for awhile (a few hot days in summer, for example). Traditionally, goldfish and koi (close relative) were kept in decorative Asian ponds, which were subjected to those same temperature changes. Thus, goldfish prefer an unmoderated water temperature. Where an angel's natural habitat would probably only vary a few degrees in temperature throughout the year, a goldfish's "natural" habitat could vary by tens of degrees throughout the year.
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