It ain't so warm here, right now (18-20C ... water is around 22C). But i suppose it is warmer than your place Luckily the tank receive sunlight during the day to warm the tank up a bit ... all the fish are always huddled in sunny part of tank (except for gars of course)
The temperature is just low enough to weaken the fish. In bad years, unprepared aro owners lose their prized fish for lack of vigilance (especially if the fish is young). I lost a batch of small paimas like this last FEB ... large fish fare OK, but are not happy throughout the ordeal