If you intend to keep tropical fish and plants and do not live in a tropical climate yourself then it will be necessary to use some form of aquarium heater. Keeping the tank in a heated room will not be sufficient. Remember different fish at acclimatized for different temperatures. It is important to get fish that are not only temperamentally suited by temperature also! An aquarium heater is necessary in this case. Before selecting your fish make sure to ask a reputable stockist about their optimal temperature requirements.

In so far as these differ, an average range of temperatures must be chosen for a community tank and in general a temperature range of between 23-25°C is best. Always have an unobtrusive thermometer kept in one corner of the aquarium so you are able to quickly and accurately able to tell the temperature of the water and also tell if the aquarium heater is playing up. While alcohol thermometers are cheap, mercury thermometers are more accurate and although not as easily available. As they say good things are hard to find. You will be able to do the job with one of the cheaper less accurate varieties, provided it is not too inaccurate. If you don't intend on keeping tropical fish then an aquarium heater is probably unnecessary and the tank will be fine provided it is kept indoors and as house temperature.

Also be aware that while many heaters are marketed as being able to be set to a specific temperature and despite as alluring as that might sound they are often inaccurate and frequently break. If you do purchase one, not only be prepared to pay more but remember to check whether it is only appropriate for a certain tank size. Often you will find manufacturers develop or make aquarium heaters for specific tank sizes. This should be adhered to.