What Temperature Should Clownfish Be Kept at?

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The first question I asked myself when I first got my clownfish was what temperature they should be kept at. Even though I knew they were hardy creatures, I wanted to provide them with the ideal conditions to extend their lifespan. That was when I began to research the topic a little deeper.

The ideal water temperature for clownfish ranges from 75 to 80 degrees F. High water temperatures may stress your clownfish, weakening their immune system. On the other hand, water that is too cold may make them weaker, slower, and sluggish.

As we move forward, I will show you how to achieve that particular range, even during winter and summer. I will also share with you my personal recommendation for an aquarium heater. This one will make your water incredibly stable. 

Also Read: Clownfish Care Guide

What is the Ideal Temperature Range for Clownfish?

Clownfish are easy enough to rear.[1] They are hardy creatures that can survive in a variety of water conditions. They also have peaceful temperaments that enable them to co-exist with the other species in your aquarium.

However, for your clownfish to thrive, you need to keep their parameters within the appropriate range, with one of the most prominent being the temperature. Clownfish thrive in waters whose temperature ranges from 75 degrees F to 80 degrees F. 

You don’t have to keep the water at any particular temperature. After all, the water in which clownfish live in the wild does not remain at any specific temperature. However, you need to ensure that the figures displayed by your thermostat fall within that range.

Some amateurs question the importance of keeping the temperature of a marine aquarium at a particular range. After all, tanks have heaters that provide you with complete control over the water temperature. But no such device exists in the wild. 

Undoubtedly, the temperature of the water in the wild is always fluctuating, especially whenever it encounters extreme weather conditions such as rain and snow. Some people believe that clownfish can survive fluctuating temperatures in the aquarium because they already survive similar fluctuations in the wild.

This argument has some merit. When the rain pours, the sun shines, and the snow falls, the temperature of the water that clownfish in the wild inhabit will change. This cannot be helped in any way. 

However, you need to realize that the water bodies that clownfish inhabit in the wild are so vast that even when these swings in temperature occur, the fluctuations are not only slow, but they are minimal.

Some changes in temperature can take an entire day to occur. In other cases, it can take a full season for the temperature to change.[2] But this isn’t the case for aquariums. Because the volume of water in a tank is so little, any fluctuations in temperature that occur are not only sudden but quite extreme.

That can have dire consequences for your fish. This is why it is crucial for you to know the temperature requirements of your clownfish and to ensure that you keep the parameters within the prescribed range. 

What Could Affect Your Clownfish Tank Temperature?

What causes the temperature in a tank to fluctuate dangerously? Well, the answer to this question consists of multiple factors. Depending on the person and the setting, one or more of these factors might be at fault:[3]

1. The Location

The location of the tank is going to have a drastic impact on the water temperature. If the aquarium is located near a window or door, it will become susceptible to the weather conditions outside. Windows, for instance, may expose your tank to direct sunlight. 

Even if you have a heater, exposure to direct sunlight will cause the temperature in your tank to spike, particularly in the summer season. On the other hand, if the window is open, winter conditions can cause the temperature in the tank to drop. 

Similar problems will arise in cases where the tank is located near a radiator or vent. That is why I suggest placing the aquarium next to a wall that doesn’t feature any windows. You should also avoid attics since the temperatures there vary widely.  

2. Artificial Lighting

While it is relatively commonplace for fish owners to position their tanks in the wrong place, most of them understand the importance of keeping their clownfish away from windows, doors, radiators, and vents. 

However, that isn’t always the case with lighting. Plenty of fish owners are unaware of the connection between their artificial light and the water temperature. They do not realize that incandescent bulbs, for instance, produce enough heat to raise the temperature in small tanks. 

Those who understand the impact lighting can have on the temperature often forget to make the adjustments needed to compensate for the presence of their lighting mechanisms. Some people simply underestimate the situation.

They know that the wrong lighting can raise the temperature. Still, because the fluctuation is small, only elevating the temperature by a few degrees, they are convinced that their clownfish have nothing to worry about. This is a problematic attitude to maintain because it only takes a few degrees in some cases for the balance in your aquarium to collapse.

3. Water Replacements

Every time you change the water in your aquarium, you affect the temperature. The larger the change, the more dramatic the impact. This is why you are encouraged to test your water whenever you perform a shift to ensure that it is still within the required range. 

Merely put in your thermometer and see what the conditions are before pouring the freshwater inside your tank. For that, I recommend using a bowl or a bucket. Generally, the difference between the two water containers shouldn’t be more than two degrees. 

4. Low-Quality Equipment

It is difficult to account for this issue. Sometimes, the temperature in your tank fluctuates because your equipment is faulty. Your thermostat might fail to display the right temperature. Also, your heater might refuse to generate the heat it was programmed to deliver. 

There are plenty of horror stories online of fish that were cooked because the heater got stuck in the wrong setting.

This is why you shouldn’t rely solely on your equipment to determine whether or not the temperature in the tank is acceptable. Look at your clownfish. Their behavior will tell you whether or not the conditions in their water are appropriate.

Why is the Wrong Temperature Bad for Your Clownfish?

Fluctuations in the temperature in your clownfish tank are not just an inconvenience. They can attract all manner of unexpected and mostly unwanted side effects, for instance:[4]

  • Clownfish do not like fluctuations in temperature. If the water becomes too warm, it can exert stress on them, not to mention damaging their immune system and causing them to suffer from all manner of diseases. If the situation isn’t corrected, your clownfish will ultimately die.

If the temperature is too low, they will become weaker, slower, and sluggish. In this case, the end result is also death. That could also be the case with the anemone or coral (in case your aquarium features one). Those creatures may even be more delicate than clownfish. 

  • The impact on the rest of the aquarium is just as problematic. Rising water temperatures are going to encourage the growth of algae which will consume even more carbon dioxide and nutrients. 
  • If you have corals, their growth rate will increase. So will their alkalinity and consumption of calcium. Because these creatures are eating and growing at an expedited rate, the waste they generate will also spike.
  • The warmer the water gets, the less oxygen it holds. A reduction in oxygen levels is going to lead to a reduction in the number of bacteria that generally eliminate the waste that your water creatures produce. 

An indicator of low oxygen levels would be when you see your clownfish swimming in the upper parts of the tanks. By glimpsing upwards once in a while, they can consume higher oxygen concentrations at the top. That is a huge warning sign that something is wrong.

As you can see, your aquarium will deteriorate quickly. Not only will oxygen levels fall, but waste production will rise, ultimately corrupting your water. You are better off keeping the water in your clownfish tank within the prescribed parameters. 

How do You Keep Your Clownfish Tank Cool in the Summer?

Summer conditions can make it very difficult for you to keep your tank water from overheating. Short of buying expensive aquarium equipment that can keep the water within the required parameters, consider the following tips:

1. Air Conditioning

This might sound odd, but it works. Keep the room in which the clownfish tank is positioned cool. You can do this by adding an air conditioning unit.[5] Keep it running all day long to ensure that the temperature in the room remains at a suitable level.

You should also keep the curtains closed. Don’t forget to position the tank away from the window. This will reduce the impact the conditions on the outside have on the temperature in the tank. Keep in mind that sunbeams may have a more significant effect when passed through a glass. 

2. Proper Filtration

A proper filtration system can keep the summer heat at bay. It will prevent the water from being exposed to higher surface temperatures for longer periods than might be healthy. When consistently mixed, the heat will diffuse efficiently throughout the entire tank.  

Experienced fish owners will also encourage you to add a bubbler or airstone in situations like this to ensure that your fish have plenty of oxygen. Warm water holds less oxygen than its cooler counterpart. If you can’t bring the temperature down, you can, at the very least, ensure that your fish are getting plenty of oxygen.

3. Take Advantage of Ice

If you believe that the temperature in the tank is rising more rapidly than your countermeasures can handle, consider arresting the situation directly. Get frozen bottles of water and add them to the tank. This cannot fail to bring the temperature down.

You may also attach the frozen bottle to the tank from the outside. That will make drastic temperature drops less likely. Either way, make sure that you measure the water consistently so that the water doesn’t get too cold. 

If the ice isn’t doing the trick, or you lack any frozen bottles on hand, aim a fan at the surface of the water. This will keep the water moving, ensuring that the same water doesn’t remain at the surface for longer than might be necessary.

4. Feed Your Clownfish Less Frequently

Warm water increases the metabolism of fish.[6] They will eat more food and generate more waste. This is at a time when the oxygen levels in the water are dropping. For this reason, you are encouraged to minimize their feeding. Give them less food than usual to combat the accumulation of waste.

However, we wouldn’t like starving the clownfish either. For that, I highly recommend that you read an article I’ve written on how often clownfish eat. I also mentioned the precise portion amounts you should use. This way, you will prevent excessive waste while ensuring the health of your fish. 

Don’t forget to perform smaller but more frequent water changes during this period. If the clownfish must suffer from the stress exerted by the heat, there is no need for them to struggle with additional discomfort resulting from dirty water. 

5. Keep Lighting to the Minimum

This goes without saying. If you are fighting to lower the temperature in the tank, you need to keep all the aquarium lights off. They are only going to generate more heat. They will make your situation worse. Some fish owners will go so far as to turn their heaters off.

The rule of thumb is to provide your clownfish with the number of light hours they get in their natural habitat. That would be approximately ten hours a day. However, if you suffer from high water temperatures, you could reduce this number to eight hours a day. 


The ideal temperature for clownfish is anywhere between 75-80 degrees F. As long as your water is anywhere between these two numbers, things should be okay. However, keep in mind that excessive fluctuations may harm your clownfish, even if the average temperature is within that range. 

I hope my article has shed some light on your issue. If you still have any hanging questions, feel free to contact me in person. I will try to get back to you as soon as I can. In the meantime, I wish you the best of luck in raising these magnificent, fascinating creatures. 


  1. https://www.fishkeepingworld.com/clownfish/
  2. https://fishlab.com/aquarium-temperature/#temperature-wild-vs-tank
  3. https://www.thesprucepets.com/aquarium-water-temperature-1381896
  4. https://www.saltwateraquariumblog.com/controlling-high-temperature-reef-aquariums/
  5. https://nualgiaquarium.com/how-to-cool-your-tank-summer-is-heating-up/
  6. https://www.aquariumfishparadise.com.au/tips-keep-aquarium-cool-hot-weather/