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Do Goldfish Need a Filter? (Filter Buying Guide)

Do Goldfish Need a Filter? (Filter Buying Guide)

I’m almost certain, all of us have seen goldfishes kept in bowls, in a friend’s house, in the local fish store, somewhere. Or maybe in a plastic tub with nothing but an airline hose bubbling away.

And somehow these “setups” always seem to work, the goldfish seems to be in great health and their keepers seem to be ever so successful.

So then why do fish keepers spend so much money on complicated filtration systems that aren’t needed? I’m here today to tell you, not to be fooled by these “maintenance free” setups. There is much more to it than meets the eye.

Do Goldfish Need a Filter? Goldfish DON’T requires a filter. They are hardy fishes and will survive in a wide range of water parameters. However, forcing them to live in less than ideal conditions is not only cruel but drastically reduces their lifespan. This is where a good filtration system comes in.

A Good Filtration System Does the Following 3 Things:

It moves the water

Stagnant water in a tank is called a dead spot.

These dead spots are detrimental to the well being of the tank because they quickly cause a buildup in excess nutrients i.e rotting food, rotting fish waste, all that bad stuff you don’t want in your tank.

Moving water prevents stagnation.

It aerates the water

Aeration is the act of introducing air from the surface into the water, increasing the oxygen content so that the fishes can have oxygen-rich water to breathe in.

Aeration also helps to keep the water chemistry stable and promotes the growth of aerobic bacteria which consumes the excess nutrients in the tank.

It cleans the water

Good filtration systems usually come in 3 stages, mechanical, chemical, and biological.

The reason is that there are many undesirable impurities in the water which we want to remove that will impact the well being of the tank as a whole. Therefore, most robust filtration systems come in 3 stages.

That said, goldfishes are voracious eaters and produce a tonne of waste and leave behind a massive trail of uneaten food quite often. This results in keepers having to do constant back-breaking water changes very often in order to reduce the number of excess nutrients in the tank.

So do you still feel that keeping a goldfish without a filter is the way to go? I don’t think so.

Choosing the Right Filtration System

Now that I’ve explained what a robust filtration system should do, let us take a look at how we can choose a filtration system that fits your tank and needs. 

There are so many options available in the market nowadays.

Sometimes even the seasoned keeper like myself gets confused. However, let me give you a simple 2 step framework so that you can choose the perfect system for your goldfish.

The volume of the tank

Knowing the volume of your tank not only puts you in a better position to select a suitable filtration system, but it also gives you the added advantage of knowing how many fishes can be housed.

Most filtration systems (if not all) come with a GPH (gallons per hour) rating which tells you the amount of water it can filter in an hour. 

That said, the general rule of thumb is 7-10 times the volume of water in your tank per hour is a good starting point.  For example, for a 10-gallon tank, you should be looking for a filtration system with 70 -100 gallons per hour rating.

Know what types of filtration systems are available

There are so many filters in the market, some are suitable for more delicate fish while others plow through thousands of gallons per hour. Below are 4 of the most common filtration systems you will see in the market today.

Sponge filters

Cheap, easy to use, dependable. The downside to this filter is that it is usually catered for smaller tanks as it requires aeration to move water through the system. This means that they are rated for very low GPH and is usually reserved for more sensitive fishes.

Here are some good options for sponge filters (link to amazon):

Hang on back (HOB) filters

Aa its name suggests, hangs on the back (or the side) of the aquarium, providing an additional volume of water for your tank, and aerating the water as it pumps water back into the main aquarium.

Here are some good options for HOB filters (link to amazon):

Internal (submersible) filters

Generally more expensive compared to the above 2, internal filters do a great job at moving water in your tank as it is submerged, essentially they also move more water as they usually have a higher GPH rating for a filter of the same size.

Here are some good options for Internal filters (link to amazon):

Canister filters

They are essentially oversized HOB filters situated outside the tank with a very high GPH rating and many layers of filtration. Therefore, they will probably do the best job at filtering water, they are also the most expensive.

Here are some good options for canister filters (link to amazon):

Once you understand these filters, you will then be able to make a sound decision on what would be best for your tank. 

What Do You Want?

Lastly ask yourself, what is it that you want to see in your tank.

Are you on a budget and are looking for something cheap? The sponge filter is your answer.

Are you willing to spend some more for a better and more aesthetically pleasing system? Your best choice is the internal filter.

Are you looking to free up as much space as possible in your tank? Probably the HOB is your best option.

Do you have a much larger tank that requires some heavy-duty filtering? The canister filter should be on the top of your list. 

Our recommendation, however, is to go for a HOB filter for your goldfish tank as they generally are low maintenance and are not too harsh for your delicate goldfishes. But any of the above-mentioned filters will also work fine.

However, this also depends on how big your aquarium is. For bigger aquariums (30 gallons and upwards), I would recommend going for a canister filter instead as it is more efficient at filtering larger volumes of water. The investment heavily outweighs the price you will pay in terms of future water changes.


Q: Can a goldfish live in a bowl without a filter?

A: Since we now know about filters and their benefits, can goldfish live in a bowl without one? Again, the short answer is yes, absolutely.

But think about it this way, imagine yourself in a tiny room for the rest of your life with only a small bucket as a toilet. Would you survive? Yes, most probably. Would it be ideal? Well, I’ll let you be the judge of that.

Filters have been designed to greatly minimize the work that the hobbyist needs to perform on the tank.

While a goldfish will survive in a bowl, the number of water changes needed to keep that fish healthy would be an immensely tedious task. 

So why not invest in a good filtration system to keep your fish healthy? And reduce your workload?

Q: How long can a goldfish live without a filter?

A: To be honest, some goldfishes spend their entire lives without a filter, and that’s a sad truth.

Most often, not because they have good owners who constantly clean and maintain their tanks, but because goldfish are very hardy fishes and will survive in almost any condition.

That said, remember that the lifespan of a goldfish can be anything from 5 to 20 years of age, which is a really long time for a fish. 

Q: Do goldfish need a filter on all the time?

A: Filters need to stay on for their whole lifespan (the filter’s life). And should only be off during specific times, like feeding and cleaning.

Filters need to be on and alive all the time because the water in the tank should be constantly moving. And constantly filtered to prevent a buildup of unwanted excess nutrients.

Keepers like myself have experienced blackouts. Or mechanical failures just for a couple of hours. This resulted in heavy loss of the livestock in my tank. Yes, filtration systems are that important.

Q: Do goldfish need a filter in a pond?

A: While the volume of a pond is much larger than the fish tank, ponds are usually situated in an outdoor environment. As such, have much more debris and unwanted material introduced into the water.

Most ponds, in fact, have rather robust filtration systems that are capable of filtering more water than filters in an aquarium for this reason.

However, some keepers choose not to have a filter because they do not keep that many goldfish in the pond. Therefore, it’s still recommended that you have a filter to keep excess nutrients at a minimum for healthy fish.

Final words

It is very possible to keep goldfish without a filter. That said, having a filter will greatly improve the lives of your fishes and is highly recommended.

I’ve been keeping fishes for years. And the times where I chose not to utilize a filtration system, I failed badly. Filtration systems are the heart of your fish tank, and should always be a priority.

Choosing a filtration system is easy, just remember the framework we talked about above:

  • The volume of water – remember the number 7-10x tank volume
  • Knowing the types of filtration systems available – sponge, internal, hob, canister
  • What do you need in your tank – Budget? Aesthetics? Or more space?

If you follow these steps, you will be well on your way to becoming a successful goldfish keeper. Thanks for reading, until next time!