Can You Put a Fish Tank Near a Radiator?

One mistake that often happens with a new aquarium is where the owner wishes to keep it. Tank owners can go around their home thinking where the ideal location is for their tank; however, they tend to find more unsuitable areas than suitable ones.

One area that fits the bill is at the side of a wall; however, there is one thing that also sits there. With this in mind, you can ask the question.

Can you put a fish tank near a radiator? While in theory, it makes sense to keep an aquarium close to a warm source to aid in keeping the water temperatures up. However, in reality, once your water temperatures are over a certain level, it causes significant issues with oxygen levels. An aquarium should never be placed next to a radiator.

Here we will look at aquarium temperatures and why sitting one next to a radiator is a wrong choice. You can also learn the effects water temperatures have on your aquarium and your fish.

Tank Temperatures vs. Temperatures in the Wild

Every fish owner knows their fish will have an ideal temperature range for the water they like to live in. Rather than being an exact temperature, these ranges replicate what the water temperatures would be in the wild.

Because of changing weather, water temperatures can rise and fall. Over a period, fish in the wild can experience a change in temperature of more than 30°F.

It can be confusing for many new aquarium owners why their tank shouldn’t sit next to a radiator when fish continually face a rise and drop in temperature in their natural habitat. The resulting answer to this is because of the speed the temperatures rise and fall.

The amount of water where the fish live will be much more than what is in an aquarium. While the temperatures can swing by over 30°F, these changes happen very slowly and may take over a day to reach the final temperature.

Fish Health and Ideal Water Temps

Once temperatures are at the edges of the ideal range, it begins to affect the health of your fish. If humans are cold or too warm, they can adjust body heat by wrapping up warm, or drinking something cold if too hot.

Fish, on the other hand, are cold-blooded. While their blood can still be warm, it means they are unable to control their body temperatures. With this, as soon as water temperatures rise or fall, so does the body temperature of your fish. When this happens, and the temperatures reach the extent of the ideal range, fish will start to feel uncomfortable.

If this happened in the wild, fish could swim to another part of the river or their habitat where water temperatures are better suited for them. It could be a shaded area if it is too hot or open water in the sun if they are too cold.

In an aquarium, it is very different for your fish, and they won’t be able to hunt out a colder or warmer area. It is this that leads to their discomfort and a rise in stress. While fish feel uncomfortable and can stress with these temperatures, it isn’t the only thing that happens to them.

The health of a fish can be affected by these extremes in temperature. If waters are on the cold side, the fish become sluggish and their metabolism slows down as a result. When waters are warm, fish become lively or hyperactive from a stimulated metabolism.

It may not sound too bad when fish are slow or move around quickly, but this causes stress in fish when the changes occur over a short period. If you are unaware, the number one reason for fish dying unexpectedly is stress.

When fish stress out, it weakens their immune system. Even with brief exposure to more than ideal temperatures can make fish less capable of fighting off illness and disease. In many cases, a healthy fish can fend these off with no worries. Once fish are temperature stressed, they are easy targets for parasites, illness, and disease that can quickly kill them.

What Happens if Water is Too Cool?

Water in an aquarium that is too cool will have a negative impact on fish. They are slow and sluggish, and if it remains at this temperature too long, they will die. Fish can feel the same as humans who are exposed to cold temperatures for extended periods.

It isn’t very nice, and it makes us all feel uncomfortable.

Water Too Warm, What Happens?

The main concern will be for your fish; however, other things can be affected if temperatures are too high. Even if you have a tank without fish, you can find warm temperatures will affect plants, invertebrates, and many other inhabitants.

One group that is severely affected by warm water temperatures is beneficial bacteria. Once water temps reach 90°F or above, then you can find ammonia spiking in your aquarium through the bacteria dying.

A new tank owner will find that warm water causes the most significant issues in an aquarium. Besides the bacteria dying and ammonia levels rising, where it burns the gills on your fish, there is another issue that can happen much quicker.

Warm water holds less dissolved oxygen than colder water. Once your temperatures rise, then your fish become more active and require more oxygen to breathe as a result of increased activity. If this goes on for too long, you can find your fish starting to suffocate, and thus dying if not attended too quickly.

Aquarium Water Temperatures, What I Need to Know

Many tank owners ask the question about placing their aquariums close to a radiator. You may see a myriad of replies on how to overcome the issue such as insulation, turning the radiator down to low, or countless other ways to overcome the problem of water that is too warm.

Even if your aquarium was large enough to dissipate the heat into the water, it could create hot spots, and these could still have a negative impact.

Aquarium owners are better finding another area, but at the same time, they need to learn what the ideal temperatures for their aquarium will be.

In this section, we will take a quick look at what the ideals are, and what you can do to help maintain these in your fish tank.

There are three categories for the ideal temperatures for fish.

  • Cold-waters: Cold water fish like the temperature of their water to be 68°F (20°C) or under.
  • Tropical waters: Fish like the water temperatures between 75-80°F (24-27°C) in freshwater aquariums
  • Temperate waters: With these ranges of water temperatures, there isn’t a specific, and they can overlap cold water temps and the tropical water temperatures. However, even here, there can be an ideal range for any fish that falls into this group.

Maintaining Aquarium Temperatures

Knowing how to manage the temperatures in an aquarium can make all the difference between healthy fish, or ones that are stressed with a high chance of dying.

One of the first things to understand is knowing the water temperature. Any tank owner does need a good quality aquarium thermometer because these prevent any guessing.

While we have seen that sitting your aquarium next to a radiator isn’t a good idea, you can also find the same if your aquarium sits in direct sunlight, or close to an AC system or opening where water temperatures can drop quickly.

You can find you need to keep your aquarium warm, or you need to keep the temperatures lower. But, all this depends on the location in your home and the region you live in.

Heating aquarium water: All you need is a good aquarium heater. You can find ones that come with a good thermostat, so as soon as the water temperatures drop, the heater turns on and starts to heat the water. One thing to note is, these do nothing to help if the water temp is too high, and you will still face issues.

Cooling aquarium water: If you live in a region where the water temps rise naturally, you may need to find a way to keep your temps lower. Aquarium fans can be an excellent simple solution as these blow fresh air across the surface of the water. You will find these are more suitable for smaller tanks rather than large aquariums. For larger tanks, you may need an aquarium chiller to keep waters from overheating.


Aquariums next to radiators are not a good idea, but tank owners can find issues in other parts of the home. While a heater and chiller can suffice, the use of these doesn’t help if the water swings in one direction.

To solve this, it is possible to have an aquarium heater and cooling controller. These detect the temperature, and can either turn on a heater or a tank chiller as required. Once you set the ideal temp, you should have little need to keep checking the temperatures as it is all done automatically.

However, using this method doesn’t mean it allows you to sit your aquarium in an area that isn’t suitable in the first place.