Do Goldfish Need A Filter?


aquarium with goldfish

Goldfish are a beautiful ornamental coldwater fish, common in many fishkeeping households. Goldfish are a great beginner’s fish because they’re hardy, meaning they can survive in fluctuating conditions. Despite their hardiness, we want to give our goldfish a long, healthy life. 

Filters are a well-known tool for keeping water quality high and stable, but do goldfish need them? The answer is yes, goldfish need a filter in their tank. Continue reading to find out why.

Goldfish Water Parameters

There are a few parameters that are very important to use an aquarium test kit regularly to ensure your goldfish is in safe environmental conditions: 

  • Nitrite and ammonia levels: 0ppm (parts per million). These chemicals can be fatal to your goldfish. 
  • Nitrate (a beneficial bacteria): 40ppm at most. The ideal nitrate range measures between 5 and 20ppm. 
  • pH: between 7 and 8 

Goldfish are a messy fish, which means they produce a lot of waste. High levels of fish waste mean that oxygen levels decrease because waste destroys carbon dioxide. This can be fatal to your goldfish because they need oxygen to survive. Think about how much harder it is to breathe in polluted cities than those with clean, fresh air. The same thing goes for goldfish: a clean tank makes it easier for them to breathe.

What Happens When Goldfish Don’t Have a Filter?

When goldfish don’t have a filter, their health can be put at risk as a result of poor water quality. Without a filter, you’ll have to constantly test and maintain the water, which sometimes isn’t enough to keep  water parameters in check. 

Benefits of Fish Tank Filters

The first benefit of a filtration system is to ensure all water parameters are in balance. Filters turn ammonia and nitrite into nitrates and keep pH balanced. Without a filter, fishkeepers will need to constantly change the water to keep the tank clean and safe, especially with goldfish. This can be a huge hassle that can be easily avoided with a good filtration system.

The second benefit is that since goldfish need high oxygen levels, filters agitate the water and enable adequate aeration. Without a filter, water remains stagnant and gets no aeration, and thus risking dangerously low levels of oxygen. 

Do Goldfish Need a Filter?

Yes, goldfish need a filter, as they need a clean and oxygenated tank in order to survive. It isn’t impossible, however, to house a goldfish without a filter. As previously mentioned, filters produce oxygen and stabilize water quality, so it’s possible to manually do this, but it isn’t easy and isn’t always effective enough to keep your fish healthy.

Filter Types

A good, strong filter effectively uses biological, mechanical, and chemical filtration. Biological filtration refers to the use of beneficial bacteria to convert ammonia and nitrites into nitrates and less dangerous chemicals. Mechanical filtration passes water through filter membranes to strain out solid particles like waste, uneaten food, and algae. Finally, chemical filtration uses chemical media additives like activated charcoal, activated carbon, and zeolite to remove harmful chemicals from tank water.

Power Filters

Power filters (also known as hang-on-back or HOB filters) are the most common external filter to use in a goldfish tank. These filters hang over the back of a fish tank, and offer strong biological, chemical, and mechanical filtration. Power filters are easy to install and maintain, come in varying sizes, and don’t take space away from the fish inside the aquarium. 

The Penguin Power Filter has a strong filtration system available for tank sizes between 10 and 70 gallons. It mechanically filters with a Penguin Rite-Size Filter Cartridge, biologically filters through the BIO-wheel to increase beneficial bacteria growth, and uses Black Diamond Premium Activated Carbon for chemical filtration.

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Canister Filters

Canister filters are powerful external filters that effectively promote all three filtration methods. They force water through a series of  filter media for biological, mechanical, and chemical filtration. The canister filter is the most effective type of filter, but is designed for larger tanks only (50+ gallons), is harder to clean and maintain, and more expensive than other filtration systems.

The Marineland Magniflow 360 Canister Filter is an awesome aquarium filter for high water quality and an extra-clean tank. Though most canister filters are difficult to clean, the Marineland Magniflow is designed to make cleaning easier and spill-free. 

Sponge Filters

Sponge filters are internal filters used alongside an air pump that biologically and mechanically filter water. They pull water through tubing from the air pump and push it through the sponge that captures debris (mechanical filtration). The sponge filter acts as a large surface area for beneficial bacteria to grow and maintain water quality.

Sponge filters are often recommended in goldfish tanks because of the water agitation. Since goldfish need high oxygen levels, they need flowing water, which you get with sponge filters.

The ALEGI Aquarium Sponge Filter is affordable and available in sizes up to 50 gallons. It oxygenates the water effectively and has a weighted bottom so it doesn’t float up to the surface of the water.

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Box Filters

Box filters are small internal filters that connect to an air pump. They are small, plastic boxes placed in the corner of the fish tank and are filled with filtration media and an air stone. With the help of an air pump, water is pulled into the box, pushed through the filter media for mechanical and chemical filtration, and back out into the water in the form of bubbles for aeration. Biological media also will grow on the sides of the box for biological water filtration. 

Some downsides of the box filter include: lack of power (inefficient), ugly, and they take up too much space. Filtration media is also purchased separate from the filter.

But, if you do go with a box filter, Penn-Plax Bubbler Bottom Filter is a simple, yet effective one.

Can Goldfish Live In Just Tap Water?

No, goldfish can’t live in just tap water. The water they live in needs to be treated with a water conditioner. There are extremely harmful chemicals in tap water that, without a good water conditioner, can potentially kill your goldfish. Additionally, chemicals in tap water can eliminate all of the good bacteria that may have grown in your water.

Can Goldfish Live Without A Filter?

Yes, goldfish can live without a filter, but it isn’t recommended. Filters maintain good water quality and aeration. Without one, you’ll need to perform water changes constantly in order to keep the environment safe and healthy.

How Long Can Goldfish Live Without a Filter?

Goldfish can spend their entire lives without a filter in their tanks, as long as the water is kept clean. The better question is: how long can goldfish live in dirty water? They can’t live long in poor water conditions; sometimes as little as one week long. Without a filter, frequent water changes are a must in order to prolong their lives.

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

1. Daily Water Changes

The most important thing when taking care of a goldfish without a filter is with daily 50% water changes. The main use of a filter is cleaning the water to ensure high water quality. Without it, water changes are the best way to maintain high water quality because it replaces old, dirty water with clean water.

2. Proper Feeding Routine

A common mistake when taking care of goldfish is overfeeding. Overfeeding can result in increased waste which damages the oxygen and good bacteria in the water. Feed your goldfish only as much as it will eat to avoid increased solid waste.

3. Introduce a Few Aquatic Plants

Live plants create carbon dioxide and can help to stabilize water parameters.

4. Beneficial Bacteria Supplements

Beneficial bacteria supplements are able to consume ammonia and nitrite to start the aquarium cycle. You can use these supplements every two weeks to help maintain good water quality.

Proper Filtration Is the Key to Being a Great Goldfish Owner

The key to being a great goldfish owner is with adequate filtration in your goldfish tank. It’ll ensure your fish’s health and happiness and is an easier, more hands-off way to keep your goldfish aquarium water clean and oxygenated. Filters can be relatively inexpensive, so when you plan to welcome a goldfish into your home, consider getting one from your local fish store for the most ideal tank setup.

Logan Price

I created this website to help fellow fishkeepers get accurate and helpful information at the click of a few buttons. I've always loved caring for fish and their aquariums, but I've certainly made mistakes along the way. So I'm hoping to help people avoid common fishkeeping mistakes so they can enjoy this satisfying hobby alongside me!

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