Do Goldfish Need A Filter To Survive All The Time?

Do goldfish need a filter to survive all the time? Always have a filter installed for your goldfish tank or in the pond. Goldfish don’t necessarily require filtering, but it’s an excellent idea to offer them top-quality filtering.

Goldfish consume a lot of food and create a lot of waste that can lead to the pollution of their water. Without a filtering system, your water from the aquarium could quickly end up contaminating your fish.

What type of filter does goldfish require?

What filter is best for a goldfish tank? There are two main kinds of filtering systems: External ones as well as internal filtering. The names suggest that external filters are placed outside of your tank, while internal filters are in the tank.

There is an absence of a “correct” type and goldfish can be kept in tanks with either an internal or external filter. But, an external filter is generally more expensive should you be able to afford one.

Because they’re outside of the tank, external filters could contain more filtration media and thus do better at purifying your water. External filters can also be stored within an enclosure to prevent impairing the appearance of your tank and also provide the benefit of not occupying valuable space within the tank.

What size filter do You Need For goldfish?

External and internal filters come in a variety of sizes. But, it’s not the dimension of the filter that’s crucial. What’s important is the “flow rate”.

Flow rate is the quantity of water that is filtered in an hour.

It is recommended to aim for at least 5x the tank’s volume per hour.

The ideal goal is to filter 10 times the size of your tank in an hour.

If, for instance, you own a tank that holds 20 gallons then your filtration system would be somewhere between 100-200 gallons per hour.

It is much easier to achieve a greater number of transactions if you utilize an external filter instead of an internal filter.

There are many kinds of filters available including those from the Fluval U Series come in different sizes so you can choose the best type of filter to fit your needs.

Clean your filter

It is crucial to not wash your filter by drinking tap water.

Instead, once or twice every year, you need to clean your filter sponges in the water in the tank.

Be sure to clean the sponges with gentle water, instead of squeezing them too hard.

This is because washing your filter sponges with tap water or squeezing the sponges too hard will kill the beneficial bacteria that live within the sponges. This would be extremely detrimental to your fish!

Internal filters for fish tanks

Fluval U series filters

Its Fluval U series filters are an excellent type of internal filter. They are among the most widely sold internal filters around the world.

They are available in a variety of models to fit different tank sizes. They are perfect for those who are just starting out. They are easy to put together are widely available and are capable of filtering the majority of aquariums effectively.

Fluval U1 Filter

Fluval U1 Underwater Filter – Designed for Freshwater and Saltwater Aquariums, Also Ideal for Terrariums and Turtle Tanks
  • Versatile Underwater Filtration: Whether you’re looking for a...
  • Filter Levels: Easy-grip water control panel and redesigned media...
  • Easy Replacement: Convenient flip-top lid allows for quick and easy...
  • Versatile Positioning: Place the U-Series filter horizontally for...
  • Tank Size Recommendation: Designed for freshwater, saltwater,...

Last update on 2024-04-09 / Affiliate links / Images from Amazon Product Advertising API

We’ll start with the U1 filter. We will begin with the U1 filter, outlining its benefits in what kind of tank it can be utilized on, as well as the pros and cons of this filter.

The U1 filter is the smallest of the U series, capable of removing the equivalent of 55 liters. It is made up of a standard internal filter container with an impeller that has a variable flow rate.

The contents of the filtration are two sponges that can be reused and the floss cartridge, which requires replacement each month or every two months.

It is cost-effective easy to maintain and clean and has a wide range of uses.

However, it is small in terms of size, since it is able to power up to 55 l. It’s not a good filter for goldfish tanks since it’s not big enough.


  • Affordable
  • Small in size
  • It is easy to disassemble and take apart and
  • Parts are easy to obtain for
  • Can be adjusted to the flow rate can be adjusted.
  • Ideal for oxygenation and current
  • The impeller and pump are both well-constructed
  • Broken or blocked impellers are extremely rare.
  • Energy efficient


  • A small amount of biological filtering
  • Floss is required to be replaced every month
  • The lid on the top can snap if it is pushed too hard
  • It can quickly become blocked if it is kept in a tank with a high level of stock

Fluval U2 Filter

Fluval U2 Underwater Filter – Designed for Freshwater and Saltwater Aquariums, Also Ideal for Terrariums and Turtle Tanks
  • Use as a primary filter for smaller aquariums, or supplementary filter...
  • Sleek design with easy grip water control panel and redesigned media...
  • Convenient flip-top lid allows for quick and easy access to filter...
  • Position horizontally for shallow tanks, larger tanks with low water...
  • Designed for freshwater, saltwater and reptile environments up to 30...

Last update on 2024-04-09 / Affiliate links / Images from Amazon Product Advertising API

The next step comes U2. U2 Filter is possibly the most widely used model in the U series since it can hold up to 110 Liters (30 gallons).).

The majority of people have between 10 – to 30-gallon tanks which is why this is the most suitable filter option for the majority of tanks.


  • Larger cartridges for filtration, which means the filter sponge doesn’t have to be washed as often
  • It has compartments for floss as well as carbon
  • The compartment is made of ceramic and has an area for sponges
  • The filter is highly flexible and can be operated horizontally or vertically
  • Cartridges can be removed easily and can be replaced by other materials, such as cut sponge
  • Filter parts are affordable


  • Is quite tall
  • Carbon and floss must be replaced every month

Fluval U3 Filter

Fluval U3 Underwater Filter Media Replacement Bundle, 2-Pack Foam Pad and BioMax, Filter Media for Aquariums up to 40 Gallons
  • Fluval Foam Pad captures large particles and debris for effective...
  • Fluval BioMax large surface area provides optimal colonization of...
  • Replacement filter media designed for use with the Fluval U3...
  • Suitable for both freshwater, saltwater and reptile aquariums up to 40...
  • Includes one 2-pack of Fluval Foam Pads and one package of Fluval...

Last update on 2024-04-09 / Affiliate links / Images from Amazon Product Advertising API

The Fluval U3 filter is essentially a similar design to the U2 however, it’s taller and offers greater biological filtration media, which allows it to clean up 150 liters.

It is a similar model with similar pros and cons to the U2 because it is based on the same style, but it could be more suited for goldfish tanks because of its higher filtering capacity.

Fluval U4 Filter

Fluval U4 Underwater Filter, Freshwater and Saltwater Aquarium Filter, A480,Black
  • Use as a primary filter for smaller aquariums, or supplementary filter...
  • Sleek design with easy grip water control panel and redesigned media...
  • Convenient flip-top lid allows for quick and easy access to filter...
  • Position horizontally for shallow tanks, larger tanks with low water...
  • Designed for freshwater, saltwater and reptile environments up to 65...

Last update on 2024-04-09 / Affiliate links / Images from Amazon Product Advertising API

Following the same design as the previous versions, the U4 is an increased height variant that is a taller version of U2 and U3 It can take in up to 240 liters of water.

In short, to summarize, the U series of internal filters are suitable for novices and experienced aquarists alike. They’re flexible effective, strong, and durable filters that keep your tank in good condition and healthy for your fish.

  • We recommend purchasing at least Fluval U2 because any other model is not sufficient enough.

Even in tanks that are 10 gallons, the U1 does not have enough filter media that deal with the messiness of goldfish.

The other options are certainly adequate filters for goldfish tanks. Just be sure to get the proper filter to water and the stocking for your fish tank.

can You keep goldfish without any filters? Fact vs Fiction

The Fiction

The notion that goldfish require a filter is false. Goldfish don’t require any filtering and live a long time as you’ve witnessed, without filtering. The longest-lived goldfish Tish was 42 years old inside a normal fishbowl.

The goldfish do not require an additional filter, but you should keep studying because there are things you should know about water filtration for goldfish.

You might be wondering how the goldfish breathe without filtering or another source of air aeration.

How can they obtain oxygen from the water?

Goldfish have a specific organ known as a labyrinth organ. The labyrinth organ functions in a way like a lung. It lets goldfish breathe in air that is room temperature and that’s why they live an extended period of time without the water.

What this means for the unfiltered goldfish is that it will absorb air from the atmosphere surrounding the bowl, which allows it to breathe in environments with low oxygen levels.

The Facts

Goldfish might not require filtering, but it’s an extremely good idea to provide them with top-quality filtering. Goldfish are a major bioload producer and produce plenty of waste.

The waste products accumulate in the water, without filtering. This means that if you keep goldfish in a two-gallon bowl that has no filter, you will need to perform periodic water changes.

Most likely every day or twice! If you don’t perform frequent water changes, then waste products accumulate in the water which could cause the goldfish to get sick. The main reason for disease in goldfish is bad water quality.

It is not recommended to keep goldfish that are not filtered in a tank or bowl and to not regularly change the water. You must monitor your water parameters on a weekly basis or more often so that you can determine if your tank is retaining ammonia or Nitrites, which could cause danger for your goldfish.

If you’re monitoring your water parameters several times a week, this will aid you in the frequency at which you need to make water changes.

Understanding the complexities of water filtration could be difficult, so if you’re an aspiring or experienced owner of a goldfish and want some more specific information about this, we suggest you visit Amazon for the most popular publication, The Truth About Goldfish.

It covers everything you have to know about creating the perfect aquarium setup, caring for goldfish, and much more!

Ideally, you should ensure that your goldfish are kept in an environment that has sufficient filtering. The fact that they are able to live in an environment that doesn’t have filtration doesn’t mean they have to.

Be aware of all the factors that can affect your ability to alter the water of the goldfish’s habitat.

If you are facing an emergency in your family or on vacation, suffer from illness have a child, or experience any other life event that you aren’t aware of, you might overlook or fail to make regular water changes that are beneficial to your precious fish.

Filtration Options

Whatever the size or shape of the bowl or tank your goldfish is residing in, there’s an option to filter the water that can ensure the water’s quality.

The most crucial aspect of filtration is to provide an environment that facilitates the growth of positive bacteria.

They require oxygen in order to survive, and therefore they cannot thrive in the absence of filtration or air aeration. Beneficial bacteria are an essential element in the nitrogen cycle which converts hazardous ammonia and nitrite into the nitrate that is safer and easier to manage.

If you’re not assisting an environment that allows beneficial bacteria to colonize then you risk the environment from the accumulation of waste products and there is nothing that can be done to alleviate it, other than the dependence on you to make water adjustments.

  • Sponge Filters: These are the simplest filters you can get, however, they are available in a range of sizes. This means that they’re often suitable for tiny spaces such as fishbowls.
  • Sponge filters take the smallest amount of solid waste from the water, yet they work by providing a large surface area to allow the colonization by beneficial microbes.
  • Sponge filters also allow aeration similar to what air stones do. This aids in maintaining the overall health and well-being of your fish, as well as beneficial bacteria.
  • Hang-on Back Filters: These are the most sought-after sort of filter. They are mounted on the side of the tank, and feature an intake that extends out into the pool.
  • This intake takes water from the tank and then pushes it through a system that provides various kinds of filters. HOB filters are a fantastic source of healthy bacteria especially when you have them with items like Bio sponges and ceramic rings.
  • HOB filters can provide chemical filtration that could help in removing unpleasant odors emanating from the tank, as well as mechanical filtering (also known as mechanical filtration) is a type of filtering that can remove any solids from the tank and then collect them in a filter floss or sponge.
  • Canister Filters: Usually the most efficient filtration method canister filters come with an intake that extends into the water. However, its body is entirely outside and under the tank. A set of hoses draws water out of the tank and is pushed through the filtering media contained within the canister before returning it back to the tank. Filtering canisters typically include media trays, which can be fully customized using the media you want to filter preference. Canister filters are generally not designed for smaller tanks and therefore, they would not be an ideal choice in the case of an empty tank or a bowl of less than 20 Gallons.
  • Internal Filters: Internal filters are installed on the tank’s wall of the tank. They function similarly to the HOB or canister filter. They draw in water via an intake and then push it through filter media after which they return the water back to the tank. Certain internal filters don’t allow you to modify the filter media you use, however, they are smaller enough for smaller tanks or bowls. They’re not the best alternative if you have fry or any other small or weak species within your tank as they may be difficult to fill the intake.


Can A Goldfish Live Without A Filter?

A filter isn’t required for goldfish tanks, however, it is highly advised to keep the water in good condition. Clean water is the primary prerequisite for goldfish! Apart from that they do not require much attention to the environment they live in. They’ll grow well and live long.

How Long Can A Goldfish Live With No Filter?

Goldfish can live for up to 12 hours without the need for filtration. They will be fine in a tank that is large enough and if they’re in a clean aquarium.

How Do You Take Care Of A Goldfish Without A Filter?

The addition of an aquatic plant to your goldfish’s aquarium will provide the oxygen needed and reduce nitrate, which is a byproduct of ammonia. Freshwater aquarium plants will also give the bowl a gorgeous natural look and also absorb gases that can cause harm to your fish.

Do Goldfish Need An Air Pump Or Filter?

As you are likely to have guessed from our other posts goldfish absolutely require filters to ensure that their water quality is in check.

Do goldfish need a filter to survive All The Time? (Summary)

Answering the question “Do goldfish need a filter to survive all the time?” is sure that it does!

Although it’s not necessary to filter your goldfish, it’s generally the best choice.

Goldfish love playing in the bubbles and currents generated by filters, and it can offer enrichment in addition to increasing the quality of water and the surrounding environment in general.

The maintenance of your water’s quality is not easy without a reliable filtering system. A poor quality water supply can result in illness and loss of life for the goldfish.

There are many great options available to filter a goldfish regardless of whether the surrounding is huge. Making the investment in an appropriate filtration system can help keep your goldfish happy and healthy for a long time.

To take the proper treatment of goldfish you will require some sort of filter.

This could be an external or an internal filter, however, we suggest the use of an external filter whenever feasible.

However, it’s crucial to recognize that using an older filter is not enough to guarantee pure water. It is essential to find the best filter to use for that goldfish tank.

It is essential to purchase an aquarium filter that can turn over about 10x the volume of your tank every hour. Ensure that you have a large enough tank. Always eliminate any extra food following the feeding of your goldfish.

With or without a filter the water you drink can be harmful to fish. This can happen when your filter isn’t strong enough your tank is too small, you allow food in the tank to spoil or you don’t make frequent water changes.

Dibyajyoti Bordoloi is the creator and author of, a third-generation experienced fish keeper and owner of a successful pet breeding farm. He is also a member of the Center for Wildlife Rehabilitation And Conservation (Assam), the Marine Aquarium Societies of North East India, and the Kaziranga Nature Conservancy of Assam.