How to Warm Betta Fish Water Easily

Keeping and taking care of betta fish is enjoyable and rewarding. In fact, bettas are one of the most amazing pets. As such, part of betta care involves warming up the water to maintain a suitable temperature in the aquarium.

How to warm betta fish water is simple. It’s advisable to get an essential heater, but worry less if you don’t have one. This article will walk you through how you can keep your fish friends warm.

Usually, betta fish are sensitive to the environment. If the temperature is too cold or too warm, it can bring about some health problems or even death.

To keep your fish comfortable, maintain a temperature between 78-80°F or 25.5-26.5°C.

Note that the fish body depends on the environment for temperature. In simple, it adapts accordingly but can’t produce heat through metabolism.

Well, read on to learn simple ways to warm betta fish water.

How to Warm Betta Fish Water

How to Warm Betta Fish Water
Red Betta fish

Luckily, there are 3 unique ways you can apply to warm betta fish water. Take a look;

Heater Submerged In the Aquarium

Betta fish water heaters are the most reliable method of warming betta fish water. If you have been figuring out how to heat fish tank water quickly, the method can be your best choice.

However, before warming the water, heaters need to warm up first. Luckily, they can take an average of only 25-40 minutes to warm up.

Afterwards, you are good to heat your water to the recommendable temperature.

Aquariums are of different sizes, and so are the heaters. As such, you need to understand that some tanks may take more time than others.

The same case with heaters; some will take more time to heat than others. On average, you need around 24 hours to completely heat your tank to a recommendable temperature for betta fish.

But to clarify, below is a table showing time estimations according to standards.

 Water VolumeTime It Takes to Warm
15 gallons15 hours
210 gallons24 hours
320 gallons36 hours
430 gallons48 hours
550 gallons60 hours

Read: How to clean betta fish tank without siphon

How Do I Know If My Betta is Cold?
White Betta

Types of Heaters You Should Use

1. Fully and Partially Submersible Aquarium Heaters

As the name suggests, fully submersible heaters are fully inserted into the tank. On the other hand, partially submersible has some parts left above the water surface.

Partial submersibles are less expensive, but unfortunately, they are not versatile. Ideally, use fully submersible heaters because they are fast and efficient.

2. Pre-set and Adjustable

Pre-set heaters are programmed to a specific temperature. Usually 78°F and turns on and off to regulate the temperature.

They are small and less expensive, purposely manufactured for small tanks.

On the other hand, adjustable heaters have two options. One has temperature markings that allow you to select numbers to set a specific temperature range.

The second option has an adjustable knob with (+) and (-) signs. Usually, they have a light that illuminates while heating.

Note that you need to have a separate thermometer because they don’t have inbuilt thermometers.

When the temperature reaches your desired level, you will have to set it with the knob, and the heater will maintain to that point.

Read: Can aquarium salt kill betta fish?

How to Set the Heaters

Usually, the heated water rises while the dense water settles down. As such, keep the heater at the bottom to make the process fast and efficient.

Install the heater horizontally at the bottom if you have a tall narrow tank. However, install the heater diagonally and keep it fully submerged in the water if your tank is short and wide.

Ideally, keep the heater close to the filter intake to distribute the heat quickly.

Recommendable Heater Sizes

To make the process effective, study the table below on the recommended heater sizes for various tank volumes;

 Tank VolumeHeater Size
15 gallons25 watt
210 gallons50 watt
320 gallons100 watt
450 gallons200 watt

Read: How to cure velvet in blue betta fish

Warming the Water Outside the Aquarium

Can I add warm water to a fish tank? In fact, it’s one of the quickest ways to warm up the water for your betta.

More so, if you decide to treat tap water and introduce your betta fish to the tank immediately.

As usual, heat your water in a separate can or tank and test the temperatures with a thermometer. You can choose to heat the whole aquarium water volume.

On the other hand, you can heat a small volume of water to a higher temperature and add it to the dense treated water.

However, ensure the water in either method has attained the recommendable betta temperature before adding it to the aquarium.

See also: Betta fish tank mates 5 gallon

Warming the Water Without a Heater

You can use various methods to warm your betta fish water if you don’t have a heater. Read on!

  • Strong Aquarium Lights

Strong bulbs designed for aquariums can release a reasonable heat amount to warm betta water. Ideally, leave them turned on for around 8 to 10 hours daily.

  • Less Energy Efficient Filter

A filtration system that releases some heat will distribute it within the tank after a while.

  • Place Aquarium Tanks in Warm Areas

Take a look at various methods you can apply;

  • Point the hair dryer directly to the tank.
  • Wrap the tank with an electric blanket
  • Set space heaters near the tank
  • Place the tank near a fireplace
  • Place the tank neat home heaters, for example, baseboard heaters.

Note that this heating method can be dangerous if the heat exceeds the recommended degrees. Always have a thermometer to confirm the readings.

Moreover, cover all the areas that may allow cold air in, especially the windows. You can also use a lid on the tank to prevent heat from dissipating.

FAQs on How to Warm Betta Fish Water

How Do I Know If My Betta is Cold?

Here are symptoms of shock as a result of the cold;

1. Lethargy
2. Staying at the tank bottom for a long time
3. Prone to diseases

Can Betta Survive in Cold Water?

Betta can’t survive in cold water for long. You have to maintain the recommendable water temperature to keep them healthy.

What Temp Is Too Cold for Betta Fish?

A temperature lower than 70°F is considered unhealthy for betta fish.

However, considering the simple methods above on how to warm betta fish water, keeping these pets healthy is easier.

Read: Is my betta fish pregnant or fat?


Florida Department of Agriculture and Consumer Services [FDACS]: Aquarium Water Quality: Total Alkalinity and Hardness

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