it's kept at room temp, which right now is close to tropical on our main floor as the weather has been quite warm...the water temp is generally around 70F year round, with fluctuations to higher temps in summer, and slightly lower in winter as would be expected. they are native NAmerican fish, so they can tolerate a wide range (they go all the way south to Florida). they are considered a warmwater fish in terms of classification of NAmerican natives (trout spp are examples of coldwater fish, walleye and northern pike are examples of coolwater fishes).
ed - the pattern does fade to an extent as the fish gets older, but males retain the pattern for quite some time (years). females end up being more drab and the ocellus disappears or just remains a black blotch.