Can An Aquarium Heater Burn Fish? Treatment & Prevention

An aquarium heater will usually come with a protector sleeve. This is to ensure the fish don’t get burned by the aquarium heater. However, there are times that the protector sleeve may be broke or fall off. When it does, most people know that heat will burn the skin, but will it burn the fish?

So can an aquarium heater burn fish?  Yes, aquarium heater can burn the fish. A fish getting burn by an aquarium heater is rare, but it happens from time to time. A burn usually occurs from a fish getting trapped between the aquarium glass and the heater.

A burn from an aquarium heater doesn’t usually happen, but if it does happen, it’s usually not a good thing. Depending on the severity of the burn, the fish will either have part of their skin tissue damaged or die from the wound caused by the burn. This is why it’s important to know how to prevent it from happening in the first place.

How To Tell If The Fish Is Burn By The Heater

Getting a burn is never a good thing. It damages the skin of the fish, causes health issues, and it hurts! Worse of all, the fish can die from the wound caused by the burn.

When a fish gets burn, it will act naturally, as nothing happens. This is a self-defense act to prevent them from attracting predators. In the wild, predatory fish will hunt for injured fish because it’s easier for them to catch. For this reason, it will make it hard to tell if the fish got burn or not.

Initial Burn

This is when the burn initially happens and it may not look too bad. The scales of the fish will look opaque and possibly a little white.  The fish will swim naturally and it doesn’t appear that they are hurt.

The Full Extent

After a few days, the full extent of the burn will be apparent. If it’s a deep burn, the damaged skin tissue will start to slough away. During this time is when the fish is at risk of secondary infections.  The tissue of the fish is exposed to dangerous bacteria and other pathogens in the aquarium water.

The fish will usually lay on the bottom of the fish tank motionless. This is due to stress caused by the burn.

At this stage, you’ll need to treat the burn as soon as possible. Without any treatment, the fish will start to become ill due to stress and secondary infection.  When this happens, the fish may only live for a couple of days before they succumb to their illness.

How To Treat Heater Burn On The Fish

Depending on the severity of the burn, you can do two things to help the fish heal from the burn. You can use salt to treat the wound or let the burn heal naturally itself.

However, if the wound seems too deep and it’s preventing the fish from swimming or moving, it’s better to let the fish die than trying to save it. The wound will initially get worse each day, and the fish will ultimately die from it.

On the other hand, if looking at the wound from the burn and the fish is swimming and moving normally, it’s worth saving the fish by trying the treatment below.  It’s best to treat the burn as soon as it happens to prevent further progression damage from the burn.

Using Salt To Treat The Burn

If the burn isn’t that bad and seems to not bother the fish at all, you can try the salt treatment. What the salt does is an act to prevent secondary infections and will help lower the osmotic pressure on the fish.

When using the salt treatment, you’ll want to put the injured fish in its separate tank. Salt can change the parameter of the water and could affect other fish.

For the salt, you’ll want to add some salt to the water at the rate of 3gms/l or 3 grams per liter of water.

Depending on how deep the wound is from the burn, you’ll want to apply some topical antibacterial/fungicide to help keep secondary infections from spreading. For this, you can use a medication called Povidone iodine, which can be found on Amazon.

To apply it to the wound, use a net to capture the fish first and gently apply the Povidone iodine medication to the wound.

In the next couple of days, the wound from the burn will start to heal by itself slowly. The wound from a light burn should heal in about a week’s time. A deep wound will probably take a couple of weeks or so. The best thing to do is keep an eye on the wound and make sure it’s not spreading.

Letting The Wound From The Burn Heal Naturally

If the burn is just a light burn on the fish skin, you can let it heal naturally on its own.  These types of burns don’t require any attention and usually will heal on its own in a couple of days or so.

However, if you want to help the fish heal faster, you can apply Povidone iodine medication to the burn area of the fish.  Simply net the fish and apply the medication and put them back in the water.

Another thing you can do to help them heal faster is to add some water conditioner such as Stress Coat, which can be found on Amazon.  What it does is add an artificial layer of mucus over the wound and prevent secondary infection from occurring.

Preventing The Heater From Burning the Fish

The risk of getting burn for the fish could be dramatically reduced if there is no aquarium heater present.  Unfortunately, for tropical and most freshwater fish, they need heat to maintain their health.

Plecostomus are known to go near an aquarium heater due to the algae.  Algae produce when there are light and heat, which makes the aquarium heater a great place for them.  The algae will grow nearby or even on the aquarium heater.  This makes it dangerous for fish like the plecostomus that eats algae.

To help prevent the plecostomus and other fish from getting burnt by the aquarium heater, there are two options you can try.  You can use an aquarium heater guard or buy a filter with a built-in heater.  Below is more in-depth for each option.

Using An Aquarium Heater Guard

An aquarium heater guard is something a lot of aquarium owners have never heard of. That’s until a fish gets a burn or another accident involving a heater.

A heater guard used in an aquarium is there to serve two purposes. The first is to prevent the fish and other aquatic creatures from coming in direct contact with the heater.

Some fish will search for a warm place to sleep or hide and the heater offer that warmth. If the fish are small enough, they may try to wedge themselves between the heater and the aquarium glass and will get stuck. This is how most fish get burn by the heater. The severity of the burn will depend on how long they go exposed to the heat of the heater.

The other purpose of the heater guard to prevent the heater from being broken or cracked by the fish. Typically, a damaged aquarium heater is caused by large aquarium fish. They can either swim by it and damage the heater or thrash an aquarium decor and it hits the heater.

Heater guard usually comes with the aquarium heater, but if it doesn’t, you can buy them online from Amazon or even make your own.

Buy A Filter That Has A Built-In Heater

Another way to prevent the fish from getting burn is to buy an aquarium filter with a built-in heater element. These types of filters tend to be canister or power filters.

The filters perform dual actions as the water passes through it. The first action is filtering the water of fish waste and other debris in the water.

The second action is heating the water as it passes through the filter. When the water is returned into the aquarium, it will be warm.  Fish are less likely to get burned this way because they are not exposed to the heat continuously.

This filter OASE Indoor Aquatics Filtosmart Thermo 100, which is found on Amazon is perfect for small to medium size tank.  It sits outside of the fish tank and can be placed behind or under the fish tank.  This power filter does the job flawlessly of filtering the water and heating the water.


A burn from an aquarium heater is never a good thing for the fish or any other aquatic creatures in the fish tank.  A deep wound from the burn will usually end up in the fish dying.   A burn can be prevented and using an aquarium heater guard or a filter with a built-in heater can help prevent it from happening.

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