What Temperature Should I Keep My Tank?

Posted in All About the Water

by: JumpMan972

A recent topic in a thread and discussion amongst friends brought to my attention that temperatures in aquariums are sometimes overlooked. For this reason, I have provided a short overview on heaters and their contributions to fish. Furthermore, I have included some of the common fish kept in aquariums by members of this forum and their recommended tank temperatures.

It is fairly easy to compare yourself to the fish, believing that if the temperature in your house is not too cold for you or your family, then it should not be too cold for your fish. I’d like to disagree. The sun is the main heating source for the fish in their natural environment.

Environmental conditions of the region where the fish are from are the environmental conditions that you, as the owner, should strive to maintain. Since all “tropical fish” are from tropical regions, their body chemistry has evolved dependencies on tropical temperatures. Fish are cold-blooded animals, meaning they can not create body temperature for themselves. Fish need the water they are in to give them that heat. This heat is necessary for a healthy metabolism. Many will notice after adding a heater or increasing the heat of their tank, the fish are more active, have increased appetites, and are slightly more aggressive. Heat is also recommended when treating diseases such as ich, a common disease found on fish from LFS. For these reasons, we must take an additional step in providing our beloved fish as close a resemblance to their natural state as we can, which includes maintaining them in suitable temperatures.

Unfortunately, the simple lighting we provide our fish do not warm our tanks enough, therefore another step is required. This step is to purchase a heater for your aquarium. There is no “one heater for all” therefore, there is a general rule of 3 watts per gallon. To ensure the correct temperature, acquire a good thermometer that is easily visible to check on. This will allow the owner to regulate the tank’s temperature and correct the thermostat on the heater as necessary. I have provided a simple chart to allow the representation of the amount of wattage needed to heat a tank:

  • 50W up to 15 gallons
  • 100W up to 30 gallons
  • 200W up to 65 gallons
  • 300W up to 100 gallons

It is not uncommon for the enthusiast to purchase multiple heaters that are suitable for their tank. Although this is not absolutely required, there are many advantages to this method. Lets take for example a 100g tank, needing a 300w heater. It is possible to have two heaters, both capable of 300w or two heaters of 150-200w each. The main advantage of this method is in case one goes out, the other will be able to maintain the regulated temperature. Additionally, two heaters will result in the heaters not working as hard, possibly lengthening their lifespan.

In the event of a power outage, there are a couple of methods that have been known to help. One of which is to wrap towels or blankets around

the tank, insulating the tank as much as possible. Other methods, usually used in conjunction with insulating the tank, involve adding treated warm water from your sink or floating containers of hot water bottles (2 liter soda bottles filled with hot water work well). These methods should help, knowing that water takes longer to cool down than warm up. Use of these techniques will allow your tank's temperature to resist dramatic change until the power is back.

Now that you know the correct wattage for your tank, it comes down to deciding which brand and type of heater you would like. There are several types of heaters, including submersible, titanium, and inline heaters. A good heater will consist of being submersible, shock resistant, having an easily adjustable thermostat, and a long length (about 6ft) power cord. The more common ones that people have experience with, including myself, is the typical submersible heater that suctions to the back of the tank. It is highly important, however, if you have a submersible heater, to turn it off if it is not in water. Newer high quality heaters come with a built-in feature that shuts off when draining a tank or if the heater is taken out of water while plugged in. It is not uncommon, nevertheless, for someone to forget or simply not know the specs of their heater. This could result in breaking the heater (if you allow it to run outside of water), potentially electrocuting your fish (at worst), leaving your fish more vulnerable (at best), denting your wallet, and more so.

Lastly, I’d like to note that not all heaters are equal. I’m sure most people want to cut corners, but heaters are one piece of equipment where you need to ensure quality. Doing some research on the internet, or even joining a forum such as Oscarfish, it is easy to become acquainted with others who have purchased cheaper and inefficient heaters. Spending the extra bucks on a reliable manufacturer can possibly help protect your fish and, in doing so, makes the hobby enjoyable for us, the aquarist.

Many tank owners are very precise when maintaining a tank. This includes research, water changes, diet, filtration, and love. These are all necessary precautions in order to create an outstanding environment for healthy and strong fish. However, due to a lack of knowledge, proper consideration may not be applied when owners decide to purchase a heater for their tank. For this reason, I have provided a short list of common fish and their recommended tank temperature. Please take a look at your temperature in your tank, and adjust if needed.

Oscar, 70-80°F, Photo Courtesy of SandTiger

Firemouth, 73-78°F, Photo Courtesy of Tom

Jack Dempsey, 72-86°F, Photo Courtesy of SandTiger

Silver Dollar, 75-80°F,Photo Courtesy of Kmuda

Green Terror, 79 - 86° F, Photo Courtesy of rED O

Convict, 68-82°F, Photo Courtesy of SandTiger

Severum, 75-85°F, Photo Courtesy of SandTiger

Pleco, 68-82°F, Photo Courtesy of SandTiger

African, 74-80°F, Photo Courtesy of rED O

Pacu, 78-82°F, Photo Courtesy of Pacu Mom

Jaguar, 77 – 97°F, Photo Courtesy of Herefishyfishyfishy

Flowerhorn, 75-86°F. Photo Coutesty of rED O

Parrot, 72-82°F, Photo Courtesy of Herefishyfishyfishyles

Clown Loach, 78-84°F, photo courtesy of Ashleigh Sterritt

Angel Fish, 74-84°F, Photo Courtesy of Kmuda

Discus, 82-89°F, Photo Courtesy of Kmuda