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    Do Betta Fish Need A Heater? Full Guide For Optimal Warmth

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    Betta fish are famous for their ability to tolerate a wide range of water conditions. They are common inhabitants of desktop aquariums all over the world. But many fish keepers wonder: do betta fish need a heater? Or are heater-less aquariums just fine for these fish?

    Bettas are a tropical fish species. They are hardy enough that they don’t require one. But adding a heater to your betta tank will give them a better quality of life and ensure they live much longer!

    Considering how small and affordable aquarium heaters are, there’s little reason not to have one. So what is involved in providing betta fish with warm water?

    We will discuss this topic in great detail below. And here is a video that offers an excellent breakdown on betta fish and their heat needs:

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    Do Betta Fish Need A Heater?

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    Bettas don’t necessarily require a heater, but having one enhances their quality of life.

    For some context: betta fish come from Thailand, in Southeast Asia. They are found in shallow bodies of water, like rice paddies and slow-moving creeks. Here, the water temperature rarely falls below 70°F. 75-80°F is more common and this is the range that betta fish prefer.

    Sometimes a cold snap might pass through the area. Since betta fish live in shallow waters they have adapted to these cold spells. But keeping them in unheated aquarium water is not good for a betta’s health.

    A stable tank temperature also promotes faster growth, and having a heater can help to sustain their preferred temperature range. Since the betta fish is not having to fight off opportunistic diseases all of the time, its fins, colors, and shape will be more pleasing to the eyes.

    How To Choose The Correct Heater For Your Betta Fish Tank – 3 Factors To Consider

    Now that we know whether betta fish need a heater, it’s time to break down how to choose one. There are hundreds of different brands and sizes out there. But these are the three factors that strongly influence the choice most fish keepers make.

    1) Aquarium Heaters And Size

    Even though every betta tank needs a heater, not all heaters are appropriate for a betta tank. All pet stores carry large clip-on heaters with metal heating elements inside of a glass tube.

    These tend to be too large for the very small tanks that most aquarists keep betta fish in. Instead, we should look at smaller heating solutions. Models that are only a few inches long.

    2) Aquarium Heater Power Consumption

    The size of the heater also correlates to how much power it consumes. The power consumption, in turn, affects how much heat it releases.

    Most aquarium heaters can self-regulate their temperature range. They will cut on when the water temperature is too low. And then turn off again once the desired temperature is reached.

    If you use a strong heater on small tanks, this balance is harder to achieve. Even brief bursts of heating can cause the temperature to skyrocket. Large heaters can even cause contact burns to fish in small tanks.

    When shopping for a heater to maintain warm temperatures, you need to choose based on the wattage. The rule of thumb is to choose a model that outputs 3 to 5 watts of power per gallon of water.

    A large tank like a 55-gallon community tank should have a heater in the 165-275W range. For 2-gallon betta fish tanks, a 6 to 10-watt heater is plenty.

    If the room tends to be cold, go with a more powerful heater. Very small tanks lose heat quickly and we don’t want our betta fish to endure constant temperature changes.

    3) Clip-On Vs Submersible Heater

    Another choice to make is whether you want a heater that dips into the fish tank. Or one that you can submerge entirely.

    Both types of aquarium heater will do the job properly. A submersible heater is easier to hide, however. If you have a carefully decorated aquascape, a heater sticking out in an obvious way can be distracting.

    On the other hand, a heating system that clips onto the side of an aquarium is easier to access. Cleaning and replacement can be done without getting your hands wet. They also tend to be more affordable

    Best Heaters for Betta Fish

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    With so many heater brands on the market, choosing the best heater for your betta fish might feel overwhelming. Fortunately, I’ve collected the very best of what’s out there in this short list!

    5 Gallon Tank Size

    A 5-gallon tank is the minimum size for a betta fish.

    For a 5-gallon tank we need to step up our power requirements a bit. The Pulaco 25W heater follows the formula of 5 watts per gallon of water volume. Plus, you get a free LCD stick-on thermometer!

    10 – 20 Gallon Tank Size

    Once you reach water volumes of 10 gallons or more, it is easier to hide a larger aquarium heater. Plants, driftwood, air stones, and other decorations all prevent a larger heater from taking up too much visual real estate.

    This model by Hitop is a submersible heater. However, the control dial can also be left exposed by the surface if you prefer easy access! Hitop also makes an affordable 100W model for 20-gallon tropical fish tanks.

    40 – 55 Gallon Tank Size

    The larger your fish tank the less you need to hold to the 3 to 5 Watts per gallon rule. Larger bodies of water don’t lose heat as quickly as small ones do. Even in a cold room, a fish tank will remain warm for hours if the power should go out.

    JamgoZoo’s 200W and 300W options are the best balance between power consumption and size. This model has in-line temperature controls with a range of 53-93°F.

    That way you don’t have to reach into the aquarium and deal with wet fingers. This tropical fish tank heater also includes a heater guard to protect your fish.

    Even brief contact with larger heaters can cause burns. Especially to plecostomus and other fish that want to attach to hard surfaces.

    90+ Gallon Tank Size

    For the largest tropical fish tanks, we need heaters that consume 300W of power or more. These heaters by HiTauing meet this need, with both 300W and 500W models.

    The heaters are well protected with plastic guards that prevent contact. While still maintaining proper water flow and circulation.

    You also have a temperature control unit that sits outside the tank. The unit’s range covers 63-94°F.

    Additional Benefits Of Having A Heater In A Betta Fish Tank

    Heaters do more than provide healthy and comfortable conditions for your betta fish. A high water temperature expands the range of community fish you can keep.

    Betta fish can live with many aquarium pets, including snails, shrimp, and even other fish. Beginners are often told that bettas are too aggressive to live with anything else.

    In truth, male betta fish are mostly aggressive towards each other. In some cases, male bettas can be kept with other fish (depending on the species) and even with female betta fish.

    Popular fish to keep with bettas include rasboras, tetras, and platies. All fish that need a warm water temperature to survive. Algae eaters like dwarf otocinclus and bottom dwellers like corydoras will also thrive!

    Cold water fish are sometimes recommended as tank mates for unheated betta tanks. Zebra danios, white cloud minnows, and other freshwater fish do thrive in room temperature tanks.

    But unlike bettas, these fish are true cool to cold-water fish and aren’t stressed by the chill. Betta fish need a heater if they are going to do well over the long term.

    What Happens To A Betta Fish If The Water Is Too Cold?

    Betta fish can tolerate room temperature water conditions for years. And even colder temperatures for brief periods.

    Temperature Fluctuations And Shock

    But if the heat leaves the water too quickly, betta fish can enter into temperature shock. Fish need time to adjust their biology to match new water parameters. That is why when you buy a new aquarium fish and bring it home, you float the bag inside the tank for 10 to 15 minutes.

    If you were to toss the fish straight into the tank, it would likely go into temperature shock. Fish going into shock hover near the surface or along the bottom. They breathe rapidly and twitch violently.

    Temperature shock is not always fatal. But it does add to the stress your new fish is already experiencing.

    Cold Water And Betta Biology

    Cold-blooded animals like aquarium fish also grow more slowly without heat. Betta fish are ectothermic animals, meaning their biology is regulated by the environment.

    They need warmth in their environment to digest their food properly. Heat also ensures their growth rate is stable and their immune system does a good job of fighting off disease. Adding extra heat is recommended if you have a sick betta fish.

    Water Temperature And Diseases

    Increasing the temperature range to 84-87°F gives your betta a better chance of a swift recovery. Heat also speeds up the life cycle of many disease-causing organisms.

    Some infectious agents, like aquarium ich, only respond to medications during certain phases of their life cycle.

    If you want your fish healthy then don’t skip on buying an aquarium heater. Not when there are dozens of excellent small aquarium heaters for smaller tank setups!

    What Happens To A Betta Fish If The Water Is Too Hot?

    It is rare to have the reverse problem: a water temperature that is too hot. This usually happens if a heater malfunctions. A betta fish tank set in direct sun can also become dangerously warm.

    Warm Water And Oxygen Loss

    Betta fish love warm conditions. But temperatures that reach 90°F or more for extended periods are dangerous for them. If your betta is too hot, it will spend nearly all of its time near the surface.

    Here the water is cooler since heat is being lost to the air. There is also more dissolved oxygen as well. The warmer water gets the less oxygen it can hold. The betta fish will also quickly breathe straight from the air as needed.

    Cooling Tank Water That Is Too Hot

    If the water is too hot for too long, your fish will show signs of stress and eventually die. You need to quickly identify where the excess heat is coming from. You may need to move the aquarium or cover a window if the tank is getting too much sunshine.

    A malfunctioning heater should be unplugged before you reach into the tank to recover it. It may also be short-circuiting and could shock you with electricity when your fingers get wet.

    If the tank temperature is at 90°F, you can allow it to cool naturally. If the temperature is much higher, I recommend performing a 25% water change and adding colder water.

    Just enough that the temperature falls to 83-85°F. Any more and you risk temperature shock in your aquarium fish.

    Can Betta Fish Survive Without A Heater? How Long Can They Live Without One?

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    Betta fish are so popular because they are some of the hardiest fish you can own. While they prefer having an aquarium heater, they will live for a long time without one.

    Even in room temperature tank water, a betta fish may live for years. So why, you might be asking, should I buy an aquarium heater?

    Because we don’t want our aquarium pets to just survive at a basic level. You could keep a dog or a person in a cold room forever and they won’t die. But they certainly won’t be comfortable, either.

    We want to provide the very best for our aquarium fish. Warm water conditions ensure a betta fish can properly fight off diseases, grows well, is active, and lives in a comfortable fashion.

    How To Keep A Betta Fish Warm Without A Heater 

    One time you may find yourself worried is if the power goes out in your betta’s tank. Electricity runs the filter, lights, and the heating system. How can you keep bettas warm without a heater?

    The first step is to slow down the loss of heat from your betta aquarium. Wrapping the tank in a blanket, towels, and other insulating materials will help it retain heat.

    Water has a high specific heat capacity. Meaning it takes a lot of energy to warm water. And once it is warmed it will lose heat slowly.

    We can take advantage of this by insulating the tank properly. Avoid opening the lid of your betta tank as well. The air above the surface of the water is also a layer of insulation that holds in heat.

    You don’t want to feed your betta fish when the filtration system is not working. So there is no reason to open the lid of your betta fish’s tank when the power is out.

    I go into even greater depth in my article on How To Keep A Fish Tank Warm Without A Heater!

    Add Warm Water To Fish Tanks

    If your betta’s tank is dangerously cold, adding warm water can raise the temperature back to a safe level. Changing tank water conditions should always be done slowly.

    If you add too much warm water too fast, your betta fish might go into shock. Especially in very small tanks.

    Instead of adding the water directly to the aquarium, you can also place the warm water in a bag. Float this bag of water inside of the betta tank. The heat will gradually disperse into the surrounding colder water.

    By not adding the warm water directly to your aquarium you also avoid sudden shifts in water chemistry. Since you likely got your water from the tap, it needs to be treated with a water conditioner.

    Otherwise, the chlorine and chloramine that municipal water treatment facilities add will poison your pet fish. Tap water also tends to be hard (high in minerals) and alkaline (high pH) as well. Two parameters that betta fish do not prefer.

    Solar Heating System

    Some aquarists are determined not to use power for their betta tanks. They instead turn to the power of the sun to warm water.

    This approach can work for betta owners that live in temperate climates, where window sunshine can warm the water in a predictable way. Or in tropical climates, like South Florida, Hawaii, or Puerto Rico.

    In Thailand, where betta fish are from, most aquarists don’t bother with heaters. The ambient air temperature range is perfect for bettas!

    So what if you live in a country where the temperature range is warm enough for betta fish? First, spend a few days monitoring the water temperature of your tank with a thermometer.

    Is your tank near a window? Direct sun can cause the water temperature of a small betta tank to rise dangerously in a very short time. Followed by a crash once the sun is no longer hitting the tank.

    Too much sun will also cause intense algae growth. Many potential tank mates love eating algae. Algae also soaks up nitrates and other waste products. It’s actually beneficial to most aquarium setups.

    But it also looks ugly since it coats every surface in your aquarium, including the front glass. All lights can grow algae.

    But direct sunlight can cause growth that gets quickly out of control. Unless you like scrubbing the glass of your fish tank almost daily, keep it out of the sun.

    Solar heating is best used only if the ambient air temperature of your home remains in a comfortable range.

    Ideal Water Parameters For Betta Fish Tank 

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    Chemistry is just as important as water temperature for betta fish. Thailand is not just a warm paradise for tropical fish. The water conditions are soft (low mineral content) and acidic (low pH).

    Betta fish are so popular because they are hardy animals. Most people keep unheated betta tanks with alkaline water. A betta will survive but it won’t thrive.

    Its colors will dull and its fins will stay clamped. You might even see stress stripes and other signs of betta stress. Overall, your pet won’t live as long as a betta fish in the right water conditions.

    If you want your bettas healthy then spend some time with an aquarium water test kit! Most pet stores carry water conditioner agents that counteract the mineral ions in tap water.

    API pH Down is one such product. It enables you to lower the pH of alkaline water with precision. A pH of 5.5-7.0 is what betta fish prefer. Soft, acidic water is especially important if you want to breed these fish!

    Ideal Betta Fish Water Parameters

    • 75-85°F (24-29°C)
    • pH of 5.5-7.0
    • 3-8 dGH (degrees of General Hardness)

    Conclusion

    The question of whether betta fish need a heater sometimes inspires debates among aquarists. Especially when fish keepers with cold water tanks have betta fish that have lived for years.

    It’s no secret that bettas are tolerant of cold temperatures. But as responsible pet owners, we don’t want to provide minimal living conditions for our animals. Especially when fish tank heaters hardly cost a thing.

    Heaters also offer substantial benefits. They keep betta fish healthy, helping them grow, digest, and ward off diseases. A tank properly warmed can also house additional fish besides bettas.

    A school of tetras or other community fish does wonders for the beauty of your desktop betta tank!


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