Betta Fish Hiding Behind the Heater: All Reasons & Solutions

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Numerous times I saw my betta fish hiding behind its heater. At first, I thought that the only reason for that was too cold water. However, as the years passed, I learned a few other factors that may force bettas to get behind heaters. To solve the issue in your tank, I decided to share all that I’ve learned.

Betta fish typically hide behind heaters when the tank’s temperature is lower than 75 degrees F. That usually happens in tanks that are too large or due to malfunctioning heaters. However, bettas also get behind heaters due to strong water currents, low water conditions, or the lack of hiding spots.

As we move forward, I will share a few tricks to solve the hiding betta issue in your tank. I will also teach you how to identify perfectly healthy bettas that merely enjoy the presence of a heater (these usually don’t require any intervention from your side).

Why Is My Betta Hiding Behind the Heater?

While it isn’t precisely the most alarming of habits, no one will blame you for showing concern because your betta fish is hiding behind the heater. Heaters are somewhat dangerous. As their name suggests, they are designed to raise the temperature of the water.

As such, they are more than capable of burning your fish, especially the internal units that sit inside the tank. To be fair, heater burns are rare. But the fact that they can happen should compel you to investigate any betta that has started hanging around the heater. 

Some potential causes of this behavior include:

1. Individual Preference

Don’t be so quick to assume that your betta’s behavior is a sign of trouble. Bettas have a reputation for cozying up to objects such as filters and heaters. If your fish isn’t showing any additional stress symptoms, you should consider the possibility that he merely enjoys occupying that particular spot behind the heater.

If you are new to aquariums, you should know that fish have personalities. Like humans, the creatures are distinct. You cannot always predict the behavior they will manifest in the tank. It isn’t all that bizarre for a betta fish to display an affinity for the heater.

This habit should only concern you if the creature begins to suffer burns due to its proximity to the device. In the absence of such harm, I suggest leaving your betta alone. The fish is probably happy as it is.

2. Lack of Hiding Places

Bettas enjoy planted tanks. However, you don’t have to limit their aquarium to plants. You can also add decorations such as rocks, caves, and pots. But plants are popular because they can transform the appearance of the tank’s aquatic environment.

More importantly, bettas use them to hide. The presence of hiding places alleviates stress because it lets the creatures know that they can always seek refuge if predators emerge. The reverse is also true. The absence of plants generates stress in fish. 

That includes fish that live in aquariums filled with small, peaceful tankmates. If your tank has no hiding places or few hiding places, your bettas will make do with the objects they can find, including the heater.[1] Once the betta decides that it feels safe behind the heater, it will frequent the location.

3. New Fish

If your betta is new to the tank, the creature’s decision to hide behind the heater shouldn’t surprise you. The process of moving fish to a new tank tends to induce stress. It takes some fish a long while to grow accustomed to a new aquatic environment.[2]

During this period, you will observe various bizarre habits that can be blamed on the new betta’s attempts to find its footing. If a new betta is hiding behind a heater, it probably doesn’t feel safe anywhere else. You have to give it time. Fight the urge to force it out of its shell. 

If anything, you should be happy that it found a spot in the tank where it feels comfortable. New bettas that don’t feel safe anywhere in an aquarium are eventually overwhelmed by the stress. Give your fish time. Don’t coax it out of its hiding place behind the heater until it is ready.

4. Convenience

Bettas typically prefer to rest near the top of the tank. In many cases, they will settle on the plants in the water. But if you don’t have any plants that reach the top, they may settle for your heater if it offers a similar vantage point.

5. Strong Currents

Fish don’t appreciate excessively strong currents in the aquarium. They induce stress because they force the fish to exert a lot more energy to maintain their position. That can wear them out in the long run.

If your betta is hiding behind the heater, that might be the only spot that gives it relief from the drag of the current. Have you seen the nice, long, flowing fins on your betta? They were not designed to contend with strong currents. 

Depending on the position of the heater, it most likely offers protection from the filter’s current. Harsh currents may also damage your betta’s fins via direct injuries.

6. Low Temperatures

That is the first consideration that runs through the minds of aquarists. Betta fish require temperatures ranging between 75 and 80 degrees. If the tank is too cold, your bettas might flock towards the heater because of the heat it offers. They want to stay in the warmest locations.

The temperature might be lower than expected because the heater has malfunctioned. In some cases, the tank is just too big for the heater to warm evenly. In other words, the water has cold spots that the betta might want to avoid, which is why it has identified and settled around the only source of consistent warmth it can find. 

While extreme temperatures are dangerous, temperature fluctuations are just as problematic. Solving that issue involves installing a high-quality heater. I personally use the Cobalt Aquatics Neo-Therm Pro Aquarium Heater (link to Amazon).

7. Poor Water Quality

That might surprise beginners who don’t understand how the water quality could compel fish to hide behind heaters. Stress causes fish to go into hiding. If you have plants, bettas will use them to stay out of sight.

But if you don’t have plants, the fish will use the other objects in the tank, such as heaters. Even if you have plants, a stressed fish could still favor the heater. As was noted before, fish have unique personalities, and you cannot always predict their preferences.

One common cause of stress in fish is poor water conditions. That includes the wrong pH, temperature, and hardness, not to mention an abundance of toxins like ammonia and chlorine. Low water quality will cause bettas to act in unusual ways. The heater is just one sanctuary among many that they might choose to hide behind.

Also Read: Stress In Betta Fish

How to Treat Betta Fish that Hide Behind Heaters?

If you are tired of seeing your betta fish behind the heater, the following steps could encourage it to abandon this particular location:

1. Improving Water Quality

As was mentioned earlier, stressed bettas would hide and are very likely to choose the heater for that purpose. Since water toxins could stress your fish, I highly recommend getting the API Aquarium Test Kit (link to Amazon). Within 5 minutes, that bundle will measure your pH, ammonia, nitrates, and nitrites.

If the toxins are too high or the pH is lower than 6.8, I suggest carrying out more frequent water changes. That will improve the quality of the water. Start by replacing 15-25% of the water weekly. Even if the conditions are insufficient, gradual adjustments are crucial.

If the fish leaves its hiding place behind the heater after a water change, you can conclude that the water quality was to blame for the betta’s behavior. 

Ideally, for betta fish, the pH should be 6.8-7.5. Ammonia and Nitrites should be 0, and nitrates should be around 20 ppm.[3] Also, the tank should be a minimum of 5 gallons. If any of these parameters are wrong, you should take steps to correct them.

Also Read: Why Is My Betta Breathing Heavily?

2. Using a Heater Guard

Before you take steps to drive the betta away from its position behind the heater, you should first ensure that it is actually in distress. As was noted above, some bettas hide behind heaters because they want to.

If your betta is perfectly happy in its position, you should leave it alone. Yet, if you are worried about the creature sustaining burns, you can protect it by adding a heater guard.[4] I don’t own it personally, although I heard good things about this Aquarium Fish Tank Heater Protective Case (link to Amazon).

This plastic cover is supposed to protect the heater from violent fish. Nevertheless, it will also create a barrier between your bettas and the heater, protecting the creature from unnecessary heater burns.

3. Introducing a Few Plants

If your betta hides behind the heater, my first advice would be to offer your fish a few hiding spots.[5] Add as many plants as the tank can take. If possible, get real plants. They have a lot of benefits to offer. But if you don’t have the time to care for real plants, fake ones will do. You can also add some driftwood and caves.

The more hiding places you add, the safer the betta will feel, and the greater the chance it will eventually leave its position behind the heater. If the fish is new, the presence of so many objects, including plants, will encourage it to explore, and that will pull it away from the heater.

The ones that I personally use are the CNZ Aquarium Decor (link to Amazon). These are plastic plants, so you don’t have to worry about cultivation. Also, they are relatively high. Combining that with their beautiful color, there is no doubt the plants will attract your betta.

4. Adjusting the Current

Betta fish that hide behind heaters will emerge from time to time, particularly during feeding times. Use that opportunity to observe them. If they are swimming at strange angles or looking like they are struggling to move through the water, the current is too strong.[6] 

The bettas won’t hesitate to run back to their chosen hiding place behind the heater once the opportunity arises. Luckily, you can reduce the strength of the current by adding plants. They will create obstacles that will slow the water down. 

A more direct approach involves adjusting the filter intake’s flow. Most devices these days feature an adjusting switch. If that isn’t an option, punch tiny holes in the output hose. That will directly reduce the strength of the flow.

5. Getting the Right Temperature

Your first step here would be measuring the current temperature. If it is too cold, check the heater to ensure that it is working correctly. You should also check the quality of the heater. Every aquarist is expected to take several factors into account when selecting a heater.

The location of the tank also matters. For instance, tanks in sunny rooms are more likely to heat than tanks in a basement because the ambient temperature is higher. The size of the tank is just as important. You need 25 watts to raise the temperature by 10 degrees in a 5-gallon tank.[7] 

The bigger the tank, the stronger the heater should be. If you can’t afford a more powerful heater and the tank has cold spots, you should improve the heater’s circulation. Some aquarists also encourage the addition of air stones under the heater.[8] The objective is to ensure that the heater distributes its heat evenly in the tank.

Also Read: Betta Fish Turning Red


Most commonly, bettas tend to get behind heaters when the water temperature is too cold for them. Therefore, the first step would be measuring the water by using a thermometer. Also, I highly recommend testing the water for ammonia, nitrates, nitrites, and pH.

If one of the parameters above is out of range, your betta will choose the heater because it is stressed. That is even more likely if your tank doesn’t feature enough vegetation or decorations. Hence, you should also add a few plants to make your fish feel safe.