Do Betta Fish Need a Filter?

Betta in aquarium with filter

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Many people with betta fish have the common misconception that their fish can survive in a stagnant cup of water. A bowl with a small fake plant or other decorative item is what we have been led to believe is adequate for betta fish. However, keeping betta fish without a filter or a heater is setting your betta up for a short, sick life. No matter what type of fish you keep, they all require a filter to process their normal waste.

Purpose of Filters in an Aquarium

Aquarium filters are responsible for removing particulates from the water and supplying substrate for beneficial bacteria that process fish wastes using the nitrogen cycle. The beneficial bacteria in the filter take a fish's ammonia waste and convert it into nitrite and then nitrate. Nitrate is a significantly safer compound, whereas high ammonia and nitrite levels can have serious consequences for your fish. Ammonia toxicity is the most common health concern in all new tanks and antiquated fish bowls.

Filters also help circulate the water in your betta's tank and provides aeration. Betta fish are labyrinth fishes with a specialized organ that allows them to breathe air. This allows them to survive in extremely low-oxygen puddles in their natural environment in tropical southeast Asia. This is not how your betta should expect to enjoy their lives in an aquarium. Survival is not thriving.


You can compare a betta in a bowl with no filter to yourself being sealed in an airtight box. Your oxygen is limited and you have nowhere to put any of your bodily waste. Occasionally, some food may be dropped in the box, but no air or waste disposal. This is the same as your betta without a filter.

Best Filter for a Betta Fish Tank

When it comes to selecting a filter for your betta, take into consideration how your betta is constructed. Their long, delicate fins are very sensitive to water currents, so be sure your filter does not overpower your fish's swimming ability. Imagine trying to swim in a ball gown against a very strong current. Internal aquarium filters are usually a good choice for a betta tank. Small hang-on-the-back filters may also be a good choice. If you have a larger filter, you may need to baffle or redirect the outflow using an extra sponge in order to ensure your betta doesn't have to swim upstream against a strong current all day.

Filter maintenance is very easy. If your betta is all alone in their tank, you will only have to do maintenance every few weeks. Remove your filter media and rinse it gently in tank water you have reserved from gravel siphoning. Do not replace all your filter media at the same time (no matter what it says on the box). This will obliterate your biological filtration, send your tank into New Tank Syndrome, and cause an ammonia spike. Instead, leave some old filter material in the filter when adding or changing to new filter pads to keep the beneficial bacteria present in the filter media.

Do I Need a Heater For My Betta Tank?

Being tropical fish, betta fish absolutely need a heater. Bettas require a water temperature around 78-82 F (25-28 C) for optimal metabolism and immune function. When you keep your fish below this range, they can have serious issues staying healthy and being able to digest their diet. A small heater is usually sufficient for most betta tanks but will depend on their overall size of the tank and where it is set up in your house. There are specific heaters made for small betta aquariums, so be sure you get the correct wattage for the size of your tank.

What Is the Ideal Betta Fish Tank?

The ideal betta tank is very easy to set up and maintain. If you are planning on keeping your betta with other fish or invertebrates, be sure to check their compatibility before you start making introductions. Betta females tend to be more social than males, but this is not always the case. Even if your fish will be living alone, starting with a 5- or 10-gallon aquarium will make maintenance easy and give your fish lots of territory to roam.

You will need a filter, appropriately sized, a heater, and some décor. Bettas are relatively "lazy" fish and like to have lots of places to rest, so choose décor items that your betta can easily rest their entire body on, such as a flat-topped castle or leaf. Avoid any decorations that have spiky bits that can tear up your fish's delicate fins. And resist the urge to over-decorate your tank. Too much stuff in your fish's tank can cause your fish injuries as they try to navigate around all the hazards in their tank. There are many small aquariums available at pet shops that can create an ideal home for a betta to live a long and happy life.

Simply put, betta fish absolutely need a filter. All fish require a filter in order to live their best lives. Bowls can be for drinks or candy but never fish.