VET APPROVED
WRITTEN BY
Dr. Luqman Javed
Veterinarian, DVM
The information is current and up-to-date in accordance with the latest veterinarian research.
Learn more »
Click to Skip Ahead
The Fiction
The Facts
Filtration Options
You may have seen goldfish living in a bowl without a filter, air stone, or aeration. You may have even owned a goldfish that lived this way. Some people have anecdotally claimed that goldfish have lived for decades in this type of setup, which often leads to discussions around the ethics of keeping goldfish in a bowl and keeping goldfish in unfiltered environments. This may have left you wondering if goldfish actually need a filter. Here are the facts you need to know about goldfish and filters.
Please Note
In many parts of the world, it may be possible to win a goldfish at a carnival, fair, or festival. We do not recommend or advise adopting a goldfish this way unless you are able to provide a suitable home for them. Legislation in recent years has led to some countries imposing a ban on having goldfish given as prizes at fairs or carnivals.
At PangoVet, we do not encourage or recommend placing goldfish in bowls as it is difficult to cater to their needs in such a setup. Goldfish are social, messy, large, and long-lived, and they should be kept in groups in aquariums large enough to house them. Some cities, counties, and jurisdictions have passed legislation prohibiting housing them in bowls.
The Fiction
The belief that goldfish don’t need a filter is incorrect. Goldfish need filtration and can live long lives in the correct setup. Your goldfish absolutely need a filter.
The role of a filter in a goldfish’s tank cannot be understated. Filtration provides your goldfish with several benefits.
All fish filters have two main functions:
- Mechanical filtration: helps trap and remove debris from the water
- Biological filtration: helps neutralize ammonia and nitrite, both of which are very toxic for pet fish
In addition to these, some filters also offer the following benefits:
- Chemical filtration: helps neutralize dangerous chemicals in the water
- UV filtration: kills harmful pathogens and some strains of algae.
The Facts
Goldfishneed filtration, and it’s a really, really good idea to give themhigh-quality filtration. Goldfish are heavy bioload producers, which means they create a lot of waste in the water without filtration.
It’s best to get a filtration system that can cycle five to seven times the volume of your aquarium every hour. For example, if your goldfish are housed in a 50-gallon aquarium, look for a filter that is rated for at least 250 gallons. If you cannot find such a filtration system, you can add multiple filters to your aquarium so that they collectively reach this target.
It is not okay to keep a goldfish in an unfiltered tank or bowl and not perform regular water changes. You should check your water parameters weekly or more frequently to know if your tank is retaining ammonia and nitrites, which can be dangerous to your goldfish. If you are checking your parameters multiple times per week, it can help guide you in determining how frequently you should be performing water changes. In a well-stocked aquarium, you should perform a weekly 25% water change.
Understanding the intricacies of water filtration can be tricky, so if you're a new or even experienced goldfish owner who wants a bit more detailed information on it, we recommend that you check out Amazon for thebest-selling book, The Truth About Goldfish.
It covers all you need to know about creating the most ideal tank setup, goldfish care, and more!
Ideally, your goldfish should be kept in an environment with adequate filtration. Just because they can temporarily survive in an environment with inadequate filtration doesn’t necessarily mean they should.
- See Also:Do Goldfish Have Seizures? Fact vs Fiction
Filtration Options
Regardless of the size or shape of the tank your goldfish is living in, there is a filtration option that will maintain the water quality. The most important aspect of filtration is providing an environment supporting beneficial bacteria development. These bacteria require oxygen to live, so they will not colonize in an environment without adequate filtration or aeration.
Beneficial bacteria are a necessary part of the nitrogen cycle, which converts dangerous ammonia and nitrite to nitrate, which is less dangerous and more easily managed. If you do not support the colonization of beneficial bacteria, you risk an environment with waste product buildup and nothing to relieve it except the reliance on you to perform water changes.
- Sponge Filters: These are the most simplistic filtration you can use, but they come in various sizes, so they can often fit in small environments like fishbowls. Sponge filters remove very little solid waste from the water, but they provide a huge surface area for colonizing the beneficial bacteria. They are usually used in tanks that hold goldfish babies (also known as fry).
- Hang-on Back Filters: These are a popular type of filter. They hang on the rim of the tank and have an intake that extends into the water. The intake pulls water from the tank and pushes it through a system that provides multiple types of filtration. HOB filters can also provide chemical filtration, which can help with unpleasant smells from the tank, and mechanical filtration, which removes solid waste from the tank and collects it in filter floss or a sponge. However, they are usually inadequate for large aquariums, and you might need multiple filters to keep up with your goldfish’s demands.
- Canister Filters: Usually the most powerful filtration option, canister filters have an intake that extends into the water, but the body of the filter sits entirely outside and usually below the tank. A system of hoses pulls water from the tank and pushes it through the filter media within the canister before returning it to the tank. Canister filters usually contain filter media trays that can be fully customized with the filter media of your choosing. Canister filters are the best option for goldfish.
- Internal Filters: Internal filters are attached inside the tank on the tank wall and function similarly to HOB and canister filters. They pull water in through an intake, push it through filter media, and then return it to the tank. Some internal filters do not provide the space to customize your filter media. They are not a great option if you have fry or other small or weak inhabitants in your tank because they can be difficult to cover the intake. They are not a great option if you have fry or other small or weak inhabitants in your tank because they can be difficult to cover the intake. They also have a drawback: they take up space within the water, limiting swimming space for your fish. They can also be somewhat cumbersome when it comes to maintenance.
- Under gravel filters: These are another type of internal filter. As the name suggests, this filter sits under the substrate, pulls water from the bottom of the tank, and returns it to the top once it’s filtered. They are not popular with goldfish because they often get clogged. They are very cumbersome to unclog since the substrate can enter them.
- See Also:
Final Thoughts
Providing your goldfish with filtration is necessary, and many animal welfare organizations consider it mandatory. The lack of a filtration system is considered inhumane for goldfish because they are exceptionally messy and produce a very high bioload in aquariums. Poor water quality can lead to illness and even death for your goldfish. There are many great options on the market for filtration for a goldfish, even if the environment is small. Investing in proper filtration will keep your goldfish healthy and happy for years to come.
- You May Also Like:Goldfish Care Guide for Beginners: Essential Steps
Featured Image Credit: luckypic, Shutterstock