Most fish should be able to cope with those temperatures, as long as you stock lightly and have plenty of surface movement. Our tanks regularly get up to 86F/31C in the summer when we have the a/c turned down during the day.
Higher temperatures reduce the oxygen in the water, so adding plants, stocking lightly and making sure you have plenty of surface movement should be OK.
Chillers are useful, but they use the same technology as an air conditioner. So, they may reduce your electricity bill somewhat, but they'll still contribute to it.
Putting a small fan blowing across the tank may help a little bit, but not that much if the temperature in the house is hot anyway.
If you do have temperature swings, that's fine, as long as they're gradual. Don't add cold water or a lot of ice cubes to a tank, as it could cool the tank too fast. |