Do Angelfish Need A Heater? (And Which One)

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There were times when I tried to raise my angelfish without a heater. To cut a long story short, they haven’t survived. The temperature fluctuations compromise their health and stunt their growth. Over the years, I’ve learned a few essential lessons regarding that topic.

Yes, angelfish need a heater since they require a temperature range of 78-84 degrees F with minimum fluctuations. That will allow them to thrive and reproduce. Achieving that precise range is difficult, which is why an aquarium heater is mandatory.

As we move forward, I’ll show you in which conditions you may do just fine without a heater (although they are quite scarce). Also, I will share with you the one I have used for years with great success.

Also Read: Angelfish Tank Setup

Do Angelfish Require a Heater?

Angelfish come from the tropical waters of South America. They are quiet, slow-moving creatures that enjoy dimly lit areas, at least in the wild. Anyone looking to house them in a tank should endeavor to replicate the conditions of their natural habitat.

Most of these conditions are not that hard to replicate, including the live vegetation and pH. However, questions have been raised about the temperature. Everyone agrees that angelfish thrive in temperatures ranging from 78 Degrees to 84 Degrees F. However, people don’t necessarily agree on the best way to achieve and maintain these temperatures.

Should you attach a heater to your tank, or can your angelfish survive without one? Well, the majority of people believe that a heater is necessary. Angelfish are hardy creatures. They can survive and thrive in waters that are slightly warmer or colder than the appropriate temperatures. 

However, consistency is essential, and this is why heaters are required. People who reject heaters argue that the weather in their area is warm enough to raise the temperature in their angelfish tank to the proper point. While this is probably true, you cannot rely on the weather to maintain the temperature in your tank.

Weather conditions keep fluctuating. Unfortunately, small fluctuations in the weather outside the tank can lead to drastic changes in the temperature within the container. Such variations are not suitable for angelfish. They require consistency in their water because that is what they encounter in the wild. 

The temperature of the water bodies in South America doesn’t change suddenly or dramatically. Any shifts that occur are gradual. This is where an aquarium heater enters the picture. Not only do these devices offer you accurate control over the temperature, but they guarantee consistency.

Don’t forget that the sun only shines during the daytime. Even if the climate in your region is warm and stable, once night comes, the temperature in your angelfish tank is going to plummet.

Some fish owners rely on the lights in their tanks to raise the temperature of the water. But it’s common practice to switch these lights off at night. And once that happens, the temperature in the water will drop, endangering your fish. A heater is necessary for anyone who hopes to establish some form of temperature stability.

The only exceptions to this rule are those fish owners whose homes are temperature-controlled. If you have an air conditioning system, you have the power to keep the ambient temperature in your home stable. This, in turn, will keep the temperature of the water in your angelfish tank stable.

Anyone else who is depending solely on the weather to maintain the temperature should rethink their strategy. Of course, finding the right aquarium heater is easier said than done.

You can’t just pluck any heater you find off the shelf. Aquarium heaters are not all the same. Before you can even begin researching the brands on the market, you must first settle on the type of heater you want. 

Also Read: Angelfish Water Parameters

What Kinds of Heaters Are Available For Angelfish?

I have been in your shoes before. Those who aren’t familiar with aquarium equipment will find it challenging to find a heater. The options are endless. Although, as we move forward, I’ll show you what to consider when buying a new one. 

When getting a new heater for your angelfish, there are a few things to keep in mind:[1]

1. Submersible Heaters

Some submersible heaters have a coiled element encased by glass. But many use a plastic tube which makes for a more durable heater. As their name suggests, submersible heaters must be submerged in the aquarium water. 

Submersible heaters are more consistent than their immersible counterparts. They also cost more money. Typically you hang those by attaching the vacuumed rubbers to your tank’s walls. Since they are quite stable, these are the ones I’ll recommend for your angelfish.

2. Immersible Heaters

This is the most common type. The heater hangs over the top, so it requires a tank with an open hood. Though, you can also make a hole in the cap. The heating element is surrounded by glass. You have to immerse it in the water for the heater to do its work. 

Immersible heaters are not perfect. The fact that they have glass components makes them fragile. They have been known to crack.[2] But they are adequate for several heating situations. They are also quite cheap, which is why beginners love them.

3. In-Filter Heaters

These heaters are inserted into the filter of the tank. They are more convenient because they are beyond the reach of your fish. But they don’t always heat the aquarium evenly. You can achieve superior results by placing your submersible heater near the inlet of the filter, and heating the water as it enters the aquarium.

Do not get me wrong. Filters are crucial to angelfish – they must be among your considerations when preparing your tank.

4. In-Line Heaters

These heaters are installed in the sump (or between the sump and the tank). They are meant to be used outside the aquarium. The fact they don’t occupy space inside makes them attractive, despite their hefty price tags. 

However, some fish are too aggressive for submersible heaters. They attack them, either cracking them over time (if they are glass) or sustaining burns. You see this in angelfish from time to time. However, an in-line heater eliminates this problem. It keeps the heater out of harm’s way.

5. Substrate Heaters

These heaters consist of wires that are inserted into the substrate. They are not that common, which is partially responsible for their hefty price tags. People like them because they supposedly promote the health and growth of the plants in your tank. 

Also Read: Aquarium Plants For Angelfish

However, I haven’t found noticeable benefits for these heaters, which justify the price range. When it comes to lifespan, I had the best results when using a submerged heater, as I mentioned earlier.

  • Your local fish store probably has a few additional variations, but these are the primary categories of aquarium heaters on the market. If you have extensive experience with angelfish, you can probably use the information above to select the right heater for your situation.

How to Choose a Heater For Your Angelfish

If angelfish, and fish in general, are new to you, you have to take some additional factors into account:

1. Static vs. Adjustable 

Static heaters are somewhat unpopular in certain circles. This is because they can only produce one temperature, hence their name. You don’t have the option of raising or reducing the temperature in your tank based on the need at hand, and some people find this frustrating.

This is why they flock towards adjustable heaters, which enable you to determine the level of heat the device generates, giving you complete control over the temperature. However, if your tank only has angelfish, you can survive with a static heater. 

This is because you know the exact temperature range you want to achieve, and there is no need to make alterations down the line. Nevertheless, if your angelfish share their tank with other species, an adjustable heater is better. That is because you have to make adjustments for the different types of fish in the water. 

2. Longevity

As was mentioned above, some angelfish are quite aggressive, and they won’t hesitate to attack any heater you lower into their water. For this reason, you are encouraged to prioritize durability. Heaters with glass components are a problem because they can crack.

Even if the idea of frequently purchasing replacements doesn’t bother you, cracked heaters are dangerous. If they don’t have any toxic chemicals and leakages are not a risk, you have to consider, broken heaters can still overheat. 

If you’ve chosen a submersible tank heater, find one that your fish can’t break.

3. Size

There is no point in buying the right heater from the right brand if it is too small for your tank. A small heater will fail in its efforts to raise the temperature in the aquarium. It will consume power without producing any tangible results, and your angels will suffer in the process.

Whenever you go shopping for a heater, keep the size of your tank in the back of your mind. Every gallon of water requires 2.5-5 watts. A 10-gallon aquarium requires a 25-75 watt heater. If you have 75 gallons, look for 600 watts.

The bigger the tank, the higher the wattage required. If you can only access weaker heaters whose wattage is lower than what you need to heat your tank, buy multiple heaters, and deploy them all at the same time. 

4. Price

This goes without saying. There is little point in setting your sights on the best aquarium heater money can buy if you can’t afford it. On the other hand, don’t go shopping with the express intention of buying the cheapest heater on the market. 

The cheapest heaters are often the least effective. Try to match the price of each heater to its features. There is nothing wrong with spending some money on a heater for your angelfish if its features are worth the price.

If you are overwhelmed by the notion of buying a heater using all the factors detailed above, ask an expert. Let someone with experience choose your heater for you. 

If you live in cold locations, try to keep the following in mind:

  • Don’t assume that your thermometer is working. Test it to ensure that the readings it provides are accurate. Otherwise, you could program the worst possible temperatures for your angels.
  • Don’t crowd your heater with decorations. Keep them away. Otherwise, they could prevent the water from circulating freely.
  • You need to position the heater in a manner that will allow the heat to distribute evenly. Try placing it near the inlet/outlet section of your filter to heat the water as it enters the tank. If the heater is submersible, position it horizontally near the bottom.
  • Don’t place your tank in places that expose it to cold conditions such as chilly basements. Doing so will force you to buy additional heaters to maintain the temperature. 
  • If you’ve chosen to use two heaters on a large tank, place them at opposite ends. This will keep the heat evenly distributed. 
  • Be sure to unplug the heater before draining your tank. Otherwise, overheating will occur, especially if the heater was previously submerged. 
  • You are encouraged to move the thermometer around every so often to ensure that the temperature is the same throughout the tank. 


Angelfish thrive in 78-84 degrees F, that is a given. If your room is well air-conditioned and you get that range outside the tank, you don’t need a heater. However, usually, that is not the case. During the day, the temperature naturally fluctuates up and down.

As humans, we are doing just fine with heat changes. Although, that isn’t the case with fish and with angelfish in particular. They require more delicate conditions, as they receive in the deepwater of the Amazon Basin. 

To achieve that, I highly recommend that you equip yourself with a proper heater. You should stick to submersible ones, since usually more stable and durable. Also, make sure to place it next to a bubbler or a filter (to spread the heat). 

Either way, I wish you the best of luck in raising your beautiful, elegant angelfish. I am sure you’ll eventually figure out the right balance for those fabulous creatures.