Betta Fish Water Temp Guide: What’s The Ideal Range?

betta fish aquarium temperature
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Last Updated: January 19, 2023 by Flora Gibbins

Most people wrongly believe that optimizing betta fish water temp is a simple matter of keeping it in a specific range. While it is true there is an optimal betta water temp range, what end of the range you keep the temperature at is very important. From disease management to longevity and activity levels, even a few degrees can have an enormous impact on your betta’s life and well-being.


Regardless of whether you use tap water or some other type in a large aquarium, there may be warmer and cooler spots depending on where the big or even a small water heater and other accessories are. Unfortunately, in smaller tanks used for bettas, there is very little difference in the temperature throughout the tank.

If the betta water temp is too hot or too cold, your pet fish won’t be able to do anything about it. This is why keeping the tank water at an appropriate temperature is very important. As a fishkeeper, this is something fundamental you learn along the way as you engage with fellow pet fish enthusiasts in a fish forum or perhaps from your very own experience.

Selecting the actual ideal temperature to keep your betta fish tank at can be a bit tricky. First, you have to decide what your goals are. In general, there is a choice you will need to make between activity levels, color brightness, and longevity. Next, you will need to observe the fish and make sure he or she is actually comfortable at the temperature you chose.

Overall Parameters

Several people go with a betta fish water temperature range between 72° and 86°F. These individuals also tend to like keeping the fish tank at 75° to 79°F.

Personally, I don’t like using just one range of water temperature for betta fish or other freshwater fish, and rarely keep my bettas in the second range.

It is much better to consider the individual betta fish and how it responds to higher and lower ends of the temperature spectrum.


Lowering Water Temperature for Longevity

To extend betta fish longevity by 6 months to a year, I recommend keeping the betta fish temperature range below 75°, but no lower than 70°.

Start out at 75° and lower the temperature 1 degree at a time using an adjustable thermostat 20-gallon aquarium heater.

Just because the betta fish seems fine during the first hour of a reduced temperature, doesn’t mean he or she will stay that way.

I recommend waiting a few days before each betta water temperature drop. Watch for signs of low temperatures and also disease.

Even though the fish will live longer, you are likely to notice their coloration isn’t as bright as it would be at higher temperatures.

If you keep bettas in slightly cold water, you may also see some slight reduction in activity. I don’t recommend dropping the temperature to a point where the betta fish is barely moving around.

The fish should still be active and alert, but perhaps not as much as at higher temperatures.

Symptoms Water Temperature May Be Too Low

When the betta tank temp is too low, betta fish will become lethargic. Even if you put food in the tank, they may not go after it quickly, nor will they eat as much.

You are also likely to see slowed gill movement and very little fin activity. In bettas, it is likely the fish will move to the bottom of the tank.

You have to be mindful of this, most of all if you’re leaving the house for a longer period of time or if you will be going for a vacation. It’s not only about their water temperature, but also some other factors like how long can you keep your bettas without food. 

Raising Water Temp for Betta Brilliance of Color and Increased Activity

Betta fish are like humans in the sense that some like temperatures a little higher, while others might do better in water that is a degree or two lower.

As a hothouse tomato, I can definitely relate to betta fish that like their water over 75°F.

Unfortunately, you can expect a six-month or more loss in longevity for these fish. Typically they will barely make it to 1 ½ to 2 years.

During that time, however, they will be much more active than betta fish living in cold water. They will also display much more brilliant colors.

For example, bettas that have iridescent or pearlized scale coloring will take on an absolutely gorgeous added dimension of color in warm water.

Bettas that live in warm water will also be more active. This can make them more amenable to learning tricks and playing with various toys in the aquarium. Note, however, that although these fishies like it warm, it’s not always a good idea to place the aquarium near a fireplace. We’ll discuss in a bit what happens when the temperature gets too high.

Adjusting betta fish water for maximum color and activity levels is very similar to adjusting for longevity.

Start out at 75°F, and work your way up 1 degree at a time. Here again, I recommend observing for a few days to make sure the fish is actually comfortable in this kind of warm water.

Symptoms Water Temperature Might be Too High

When the water is too warm, bettas will show a dramatic increase in coloration. This may include some redness in the gills.

They will swim around a lot, but it may also be very erratic. I often describe it as they are trying to swim away from something, but having no place to go.

If you put food in the fish tank, the betta may also go after it differently.

Usually, bettas are somewhat dainty in how they approach each morsel of food. When the water is too warm, they are more inclined to snatch.

Importance of Stable Water Temperature

Keeping the water temperature as stable as possible is essential for seen and unseen inhabitants of the betta tank. This includes beneficial micro-organisms as well as harmful ones.

Betta Fish Temperature - What Temperature Should Your Betta Fish Tank Be? -

Insofar as the fish itself, stable temperatures reduce stress.

There is no such thing as an aquarium that will ever be as comfortable and relaxing for a fish as a natural setting. This applies even to bettas that may spend their entire life in a puddle of water no bigger than a shoebox.

In fish, the relationship between stress levels, water temperature,  and immune system health is well documented. Even small changes in the betta water conditions can lead to immune system weakness or full collapse.

Frequently Asked Questions

1. Why are bettas and other tropical fish described as being cold-blooded?

Let’s say you keep your room temperature at 75°F. If you take your body temperature, will be around 98°.

This happens because your body has some internal methods for maintaining a stable temperature that can be higher or lower than the external ones. As a result, humans and many other animals are referred to as being “warm-blooded”.

By contrast, bettas, cold-water fish, and other tropical fish cannot adjust their body temperatures to be different from the surrounding water. If the water temperature is at 75°, then that is what the betta temperature will be.

To adjust betta fish temperature, they must move to a location where the temperature matches their comfort level.

2. Why do water temperature changes increase the risk of disease?

There are two reasons. As previously mentioned, fluctuations in temperature have a direct and negative impact on the fish’s immune system.

This can occur because betta temperature translates to an increase or decrease in metabolic levels. It can also create stress cascades that cause immune system collapse.

Another factor is the impact of water temperature on opportunistic infections.

One of the most interesting things about disease is fish don’t always get sick if a pathogen is present. In some cases, there may not be enough organisms present to lead to a noticeable disruption.

Or, the fish may be able to fight the disease to a point where you don’t actually see it as being active.

Typically, fish come with dozens to hundreds of opportunistic infections. As long as the water chemistry and temperatures are right, the disease won’t break out.

Temperature shock or an increase or decrease in temperature can spur a semi-dormant disease into increased activity. If the fish happens to have injuries or other problems, then you will see a breakout.

As you can see in this video, fish diseases can show up very quickly and give you little time to choose the right medication.

3. What diseases can I expect to see if the water temperature goes too low?

Ich followed by velvet are the two most common disease breakouts when the water temperature goes too low and then returns to normal.

You may also see the emergence of fin/tail rot or cottonmouth fungus. However, I have seen those more often when the temperature goes up.

4. If the temperature is too low, is my fish really dead?

At first, this may seem like an odd question. Tropical fish and other aquarium fish, like the neon tetra, are often shipped at lower temperatures to ensure a sluggish metabolic rate.

Once fish arrive in the store, they must be revived. This can take several hours.

Therefore, even if the temperature of your betta tank goes below the ideal temperature for betta fish, the fish may still revive. Just let the fish sit in the water in the ideal betta temperature range for a few hours and increase the airflow in the betta tank.

There are no guarantees this will work, but you can still try.

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The best temperature for betta fish is a matter of what will work best for each individual fish.

If the betta in question can tolerate lower temperatures, then you can look forward to having an aquatic pet that will live a little bit longer than the high end of the species’ lifespan.

Bettas that prefer slightly warmer temperatures may have shorter lifespans, but they will display brighter colors and be more active. 

What Temperature Should Betta Fish Water Be? -

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