How to Keep Aquarium Temperatures Constant

One of the keys to keeping tropical fish is to maintain a steady temperature in the aquarium where they live. Tropical fish come from climates where the water is warm, and if the temperature drops too low, those fish become susceptible to a number of diseases and chronic conditions. Raising the temperature to an acceptable level and keeping it steady is one of the best ways to ward off disease and maintain the good health of your fish.

Things You'll Need

  • Heater
  • Thermometer
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Instructions

    • 1

      Purchase an aquarium thermometer with an adjustable dial that lets you set the desired temperature. These heaters are much more reliable than the kind that lack a temperature control mechanism.

    • 2

      Submerge the heater in the aquarium and fasten it with the supplied suction cups. If you have a small aquarium of 5 to 10 gallons, try putting the heater in the center of the back wall of the tank. For larger aquariums it is often best to use two heaters and place one at each corner of the tank.

    • 3

      Place a thermometer on one corner of the tank, in a spot where you can see it easily. Use this thermometer to monitor the temperature of the water each time you walk by the tank.

    • 4

      Add a floating thermometer to the tank as well. Compare the temperatures shown by the two thermometers and adjust the heaters as needed. The heater has a small plastic knob at the top. Simply turn the knob to the desired temperature setting, then wait about 30 minutes and recheck the temperature in the tank. If the heaters are not maintaining a steady temperature they should be replaced as soon as possible.