Hot Weather (above 30°C)

Since setting up the tank, there have been one or two weeks each summer where the temperature has risen to over 30°C. At this temperature the fish will be struggling. There are several things you can do to allieviate this: turn the light off; place a damp towel over the tank; open the windows and point a fan at the tank; increase aeration levels; be stringent about water quality and treatment; change water and filter layers more often than usual.

I tried all of these, and the tank temperature was still consistently over 30°C, so I did something that fishkeepers are told is terribly wrong... I added ice to the tank. However, I did this extremely carefully. I put two or three lumps of ice at a time into a freezer bag, and floated that in the filter section of the tank, so that the colder water would be mixed into the tank and not in direct contact with the fish. I stirred the water gently with a net every few minutes after adding fresh ice. It only took a few minutes for each small bag of ice to melt, and I changed it every half hour or so. It worked, but I would still suggest that you only use this method as a last resort. It is labour intensive for you, and probably a shock to the fish. I used it only when my fish were resting and gasping all the time, and I felt I had to act. It takes the tank through the few really hot days of the year.

Cold Weather (e.g. heater broken, power cut)

If your tank is without heating, for example the heater has broken or there is a power cut, don't panic. If it is just that the heater has broken, crank up the heating in your house to 25°C or thereabouts and keep an eye on the tank to make sure it does not cool too far until you can replace the heater. Aquarium lighting will help to keep the tank warm too.

If you are unable to heat the house, throw an old duvet or a blanket over the tank, and try to keep the room free of drafts. This will keep heat loss to a minimum.

If the loss of heating is due to a power cut, remember that the filter is the main priority. If the filter is off for more than a few hours there is a risk of bacterial die off, and of producing toxins. If you smell hydrogen sulphide (rotting eggs) be very suspicious - this will harm the fish. To keep the bacteria in the filter alive, keep warm water gently flowing through the media as much as is possible.

When you are able to re-heat the tank, do so gradually so as not to shock the fish.