Do Betta Fish Need Heaters?

In most cases, yes, betta fish do need heaters. Read on to find out why.

Thermometer in a betta fish tank

What temperature should a betta tank be?

In the wild, bettas live in south-east Asia. In other words, a place with a very warm, tropical climate.

Bettas are hardy fish and thrive happily between 78 ℉ to 82 ℉. This is something to remember when caring for a betta. Chances are you’ll need to heat your aquarium as usually a house will sit at room temperature (70℉), which is too cold for a betta to stay healthy.

The water temperature for a betta should never drop below 74℉.

How Aquarium Heaters Work

Aquarium heaters are a submersible tube-like instrument used to keep a constant, adjustable aquarium temperature. Some heaters are also manufactured to give a pre-set temperature, rather than have an adjustable option.

The pre-set heaters tend to be cheaper compared to adjustable heaters, although the adjustable heaters tend to be more reliable for keeping a consistent temperature.

They can be placed or stuck onto the side of an aquarium or they can sometimes be inserted into the filtration compartment of a nano / compact aquarium. They can range in size.

It wouldn’t be difficult to find one to fit the size of your betta aquarium. An important factor to consider is the larger the volume of the aquarium, the higher the watt the heater should be. A good measurement to follow is one watt per litre (or 5 watts per gallon).

To put it simply: a 15 watt heater would not be able to heat a 30L aquarium substantially for a betta, even with an adjustment dial. Something like a 25 watt heater for a 20L would be fine – perfect even.

How to set up an aquarium heater for a betta

Instructions will usually be given on the heater box, but setting one up for an aquarium is fairly straightforward; simply submerse it in the aquarium.

If the heater has suction cups attached, you can anchor it to the wall of the aquarium. It's best to place your heater sideways near the filter as the filter pump will help circulate the warm water around the aquarium. There should be a dial somewhere on the heater to allow you to adjust the temperature. For a betta, set the temperature to about 78℉.

It may take time for the heater to start up, then it takes time for the aquarium water to reach the given temperature.

Check the temperature with an aquarium thermometer (these are easy to come by and inexpensive).

Once the water reaches 78℉ it should stay at that temperature, give or take.

Be sure to check the temperature regularly. The aquarium may change temperature slightly from time to time depending on the environment it’s in, e.g a house in a country where the seasons vary in temperature a fair bit.

Also, the heater may break, stop working or turn off for whatever reason. Over time heaters tend to deteriorate.

We have a digital thermometer for our aquarium that constantly displays the temperature; we check the temperature whenever we look at the aquarium, just out of habit.

Examples of Aquarium Heaters:


Adjustable Aquarium Heater by Interpet (view it here on Amazon)

We've found this heater to be reliable and keep aquariums at an accurate and consistent temperature. The heater also has a thermometer built in so it's easy to tell if the heater is functioning as it should.

Adjustable Aquarium Heater by Orlushy (view it here on Amazon).

Adjustable Aquarium Heater by Fluval (view it here on Amazon).

Examples of Thermometers:

Digital Aquarium Thermometer


Zacro digital aquarium thermometer (view it here on Amazon)

We've found this one accurate and easy to read.

Marina Floating Thermometer (view it here on Amazon)

We've also got this one floating in our aquarium. It's easy to read at a glance with a green zone that shows you the ideal temperature range.

A note about aquarium thermometers

As mentioned, you can grab an aquarium thermometer for a low price. Sometimes you can get stick on ones, a submersible mercury thermometer or even a digital one.The more expensive ones usually give a more accurate measurement, but as long as you can clearly see the temperature of your aquarium is sitting between 78℉ and 82℉, you don’t need anything fancy.

Digital aquarium thermometer suitable for betta fish

Does my betta need a heat mat?

It needs some sort of heating apparatus. Generally, heat mats aren’t used for aquariums. It’s usually not a good idea as they don’t tend to be waterproof and don’t come with an adjustable temperature. We’ve seen that external aquarium heaters are on the market, with even Zoo Med selling a betta bowl heat mat, but it’s best just to stick to a standard aquarium heater.