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Yes, aquarium heaters can burn fish, though it’s at best a rare occurrence, and more a case of proximity than design.
I say it is more a case of proximity because for a fish to sustain heater burns, it must be pretty close to the heater for an arguably long time.
For instance, your fish will get heater burns if stuck between the heater and aquarium walls or when resting or hiding close to the heater.
That said, your fish is more likely to get burned by certain types of heaters than others. Generally, inline (external) aquarium heaters that are installed in the outflow line of your aquarium filter are safe in contrast to internal units that go inside the fish tank.
Therefore, If you must use an internal heater, and are wary of your fish getting burned, consider purchasing a heater guard to prevent accidents.
Read on for more insight on how to prevent, detect, and treat heater burns in an aquarium.
How To Aquarium Prevent Heater Burns in Fish
Bottom-dwelling fish like plecos, kuhli loach, and inverts like shrimp, as you may have notice, like hanging around aquarium heaters.
They swim like to around heaters to get algae that grow on them or even to lie (rest) on the units. For that reason, even when it’s not too common for fish to get heaters burns, it is important that you learn how to prevent an incident.
Fish feel pain. If they realize the heater is burning them, they will swim away. Unless the fish can’t, maybe it’s stuck or hiding from a bully.
The first and easiest way to do this is to maintain a good current and flow over the heater to ensure the heat produced is quickly distributed across your fish tank.
To do this, position your heater near a filter inlet or outlet or a circulating pump. Moreover, submersible aquarium heaters can be installed vertically or horizontally near the bottom of the tank for best results.
However, do not let you heater touch the gravel or aquarium glass because this could lead to a temperature difference that has the potential to break the glass.
The other quite straight forward way to keep your fish from getting burned by an aquarium heater is adding a heater guard.
What is an Aquarium Heater Guard
An aquarium heater guard, also called a heater guard protector, is a simple plastic cover that slides over your aquarium heater. It works to protect the heater from damage caused by boisterous fish and falling plant debris. It also keeps the heater from coming into direct contact with aquarium glass, decor and the fish.
In the context of this topic, an aquarium heater guard is especially useful when you have fish like plecos that won’t stop hiding or resting on the heater. More so because no amount of water current or flow can effectively protect a fish if it comes into direct contact with the heater (especially close to the heating element).
Many quality aquarium heaters now come with an integrated guard but incase your does not have one, you can purchase it separately for less than 10 dollars.
How To Tell Whether Your Fish Has a Heater Burn
Just because a fish got a heater burn does not mean it will show clear signs. Sometimes the burned fish will even keep hanging around and resting on the heater.
Besides, a lethargic fish showing signs of weakness is a sitting duck, vulnerable to all sorts of attack, especially in a community with belligerent fish or species that establish a pecking order.
It’s therefore quite tricky to know your fish got burned, and more challenging if not familiar with a fish’s tendency of hanging around heaters or didn’t see your fish stuck by the heater.
So, how then do you know if a spot on your fish is a burn, an infection or an injury of a different kind.
The only sure way is to investigate any unnatural markings on your fish body especially on those you know like being around heaters.
Smaller burn marks are difficult to see because they usually don’t look too bad. Most times, the skin will only look pale or white-ish, and the gills more transparent.
The scales on the burned part might look discolored like a pale version your fish’s natural tone.
But if the burn is severe, the mark will turn into a wound in a couple of days and might even be flesh deep with the scales and skin completely gone.
Deep wound like this requires more attention because the fish is at that point exposed to secondary infections.
How to Treat a Fish with Aquarium Heater Burn
If you are sure your fish got burned, I recommend you follow these four steps in the given order. However, you will want to first assess the severity of the wound, plus avoid overacting because unnecessary actions will only put your fish under more stress.
#1 — Add Salt in Your Tank (Salt Bath)
A wounded fish, either from burns, infections or attack from other fish, is usually faced by two immediate dangers.
First, the fish mucus surface and skin will be affected, so will be the immune system, thus instead of the fish channeling its energy on osmoregulation, it will direct all it’s effort and resources to healing.
The second danger is usually secondary infections through the open wounds, which is further aided by the fish weak immunity.
So, what you want to do once you have assessed the wound is either add salt to your aquarium water or give your fish regular salt baths to help the fish with osmoregulation so it can focus on healing.
This will ensure your fish remains strong and active, more so during meal times, which is another function that weakness can affect and worsen the situation.
I recommend adding 1 tbsp of salt per 3 gallons of water either directly or by dissolving it in a small cup of water first.
If the wound is too severe or when you are weary of adding salt to your freshwater aquarium, you might want to put the affected fish in a hospital tank.
In the absence of additional stress, fish with mild heater burn wounds will probably heal on their own. Keep an eye on the wound, and if it does not look better in the following several days, move your fish to a hospital (quarantine) tank for targeted treatment.
#2 — Use A Broad-Spectrum Antibacterial (+Fungicide)
To prevent secondary infections following a burn wound, it is advisable to use preventative antibacterial and/or fungicide. But, you’ll want to be careful when adding the medicines because some can disrupt your aquarium chemistry.
Also you may want to add the medicines once you’ve moved your fish into a quarantine tank, and even consult an experienced aquarium professional before treatment.
Please note, know that some antibacterial and fungi treatments are targeted for a specific infection, while others (broad-spectrum antibiotics) control both or either gram-positive or gram-negative bacteria.
What you want to use on a fish with an aquarium heater burn wound is a broad-spectrum antibiotic, unless the fish already has a secondary infection then you can use the specific treatment.
#3 — Use Stress Coat (Wound Seal) in Your Tank
Aquarium heater burn wounds does affect a fish protective slime coat causing a loss in essential electrolytes through the skin, which leads to suppression of the immune system.
Therefore, together with other treatments, you also want to focus on restoring this protective coat. To do so, add wound seal in your aquarium with water changes.
Most stress seal (wound seal) remedies will have application directions on the packaging.
#4 — Keep Your Aquarium Clean
As with all infections and injuries, keeping your aquarium clean helps your fish heal faster and keep secondary infections at bay.
So, remember to do regular water changes, remove uneaten food from the tank, and make sure your aquarium filter is working effectively.