There are usually three variations in freshwater fish: tropical, temperate and coldwater.

Tropical fish are generally fish that come from warm climates where the water doesn’t often drop below 22 ºC. In most locations, particularly in the Northern Hemisphere, these fish will require a heater almost year-round. Temperate fish are found in cooler environments, often farther north than their tropical counterparts. These fish generally live in the temperature range of 18ºC – 22 ºC. While they don’t usually require a heater, you can add one as security on colder nights.

Tropical fish are just as easy to keep as coldwater and temperate fish and are just as hardy. The only difference is the addition of a heater; for this you get access to an abundance of fish species, as tropical environments tend to be much more diverse than cooler ones.

In years gone by, heating a tropical tank was a major issue. However, today it has become very simple thanks to the invention of the aquarium heater. The typically available version is the thermostatically controlled aquarium submersible heater, which allows you to choose your temperature and it will automatically maintain it, clicking on and off as needed.

These heaters generally come in a range of sizes from 25 watts to 1000 watts. The wattage power that you need is determined by where you live, your tank size and the temperature you want your aquarium to be kept at.

To calculate what wattage of aquarium heater you need, follow our quick step by step guide below.

When placing the heater in the aquarium, put it as low as possible without allowing it to touch the gravel and ensuring there is a fair amount of circulation around the heater. Many people prefer to hide the heater with hardscape or aquarium plants, which is completely fine and will add to the natural feel of the aquarium. However, bear in mind that you want to allow water to circulate around the aquarium and heater.

It is very important to note that you must be confident that your temperature is suitable for all the species within your tank and that the temperature is actually being maintained. To ensure this, place an aquarium thermometer within the aquarium and check it as part of your daily to-do list.



Wildlife One is an online magazine and writing label under the branding of wildlife writer, Alexander Howson. Wildlife One is dedicated to bringing readers a range of inspirational articles that cover all aspects of wildlife. Promoting conservation, animal welfare and the protection of wildlife.

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