Consistent temperature is essential to aquatic life. As pets, aquarium fish have very few threats on their lives. Of these threats stress is the most frequent killer of our beloved fish.
As the temperature changes in the aquarium our fish must adapt to their new environment. Constantly changing between a harsh summer and chilly winters stress fish to no end. This stress will weaken your fishes immune system, greatly increasing the risks of ich, parasites and eventually death. It is for this reason that using the right aquarium heater is so important to aquatic life. Always check the temperature your fish should be housed at before purchasing. Pairing goldfish and discus will result in certain death for one of the fish due to the great difference they require.
When adjusting the heat of your aquarium it is vital that you never adjust more than a single degree per day. Yes that is a very slow rate but it is necessary to ensure the fish do not quickly become sick. Likely if you discover your tank is too hot or too cold it will have been in that state for a few days or even over a week, making the 2-5 days you adjust the temperature short in comparison. Your fish will thank you for taking it slow.
The best times to adjust your aquariums heat are in the beginnings of spring and fall. Do not wait for summer to turn your aquarium heat down, as most houses will rise a few degrees in one day once the summer sun comes out. Likewise warming the tank up right before an on coming cold front helps prevent the aquarium from quickly cooling down to below optimal temperatures. If you maintain the same house temperature all year you may readjust your aquariums back to their normal heat as your house becomes stabilized, but for homes who rise and fall between 68 and 78 degrees owners should take a special note on their aquariums at the seasons change.
Living in a high temperature area means owners may have to buy coolers to keep their tanks cool. Humidity from costal regions does not hurt the fish any, while high heats in arid states can boil the tank and double evaporation rates. While aquariums should never be near the windows, the effects of poorly placed aquariums will become more evident than ever during summers. Keep the coolers on during the day and close the curtains at night. Any incoming heat may hit your aquariums before you awaken and reactive your coolers.
Check your tanks temperature daily during these uncertain seasons and adjust your heaters as frequently as needed. Those with more precise aquarium heaters will get the benefits during the changing weather while value heaters may see the real price of skimping on equipment.