Do Goldfish Need a Filter? The Answer Probably Won’t Surprise You!

Last Updated on September 18, 2021 by cmoarz

Do goldfish need a filter to live? Absolutely not! Do you see goldfish using filters in the wild? No of course not!

But wait! There’s more!

So your saying Goldfish don’t need a filter? Wait that can’t be right though?

Your wrong actually. The only thing goldfish needs to live in this case is clean water quality. However, You won’t have clean water quality without a filter.

Do you see what I did there?

So to answer the question, Do goldfish need a filter? The answer is no they just need clean water, But to maintain clean water quality you need a filter. So I guess the best answer to the question is yes, Goldfish aquariums do need a filter to maintain clean water perimeters in which the goldfish need to survive.


What happens to your goldfish if it doesn’t have a filter?

It goes without saying I think, Your fish will die. Or at the least, fish sick. It’s just that simple. At least, Without a lot of maintenance from you!

Consider this, the average lifespan of a goldfish is 12 years. The average lifespan of your goldfish without a filter and constant maintenance will be about 3 months.

“Ah, but you said I have an option, constant maintenance!”

I did say that, And it’s true! You have the option of doing more maintenance than you ever thought possible! To maintain a filterless goldfish tank you have 2 options:

Cleaning the water every 2 days for the next 12 years


Lots and lots of plants and a diverse lively ecosystem

Let’s talk about option 1. Cleaning. Using a 10-gallon tank as a reference.

Every other day you will need to siphon out 5 gallons of old water and replace it with new. You will need to vacuum the substrate and try and cram in as many densely packed porous surfaces as possible to encourage friendly bacterial to break down ammonia.

However, even with that ammonia breakdown, you still end up with high amounts of nitrates that need to be removed.

Needless to say, that’s a lot of work for trying to avoid a 20$ filter media. (I recommend a sponge and airstone filter, btw. As ez as 123).

Now, For Option 2! The filterless Echosystem option!

This generally is for more advanced hobbyists who already have a large variety of plants and other life in their tanks already. The idea is to make the perfect cycle for your goldfish tank. With all these bacteria, algae, and other life around breaking down ammonia eating up nitrates, etc. pretty much just leave CO2!

Which will be absorbed by the plants in this case, which you’ll have a lot of because your gonna want to pack that tank full if possible using every square inch of surface area with plant life. Doing this keeps oxygen high so your fish can breathe easily even without any filtration media/air pumps etc…

The plants will use the waste faster than it can muck up the water, coupled with some shrimp, snails and various other types of critters that live inside your substrate, this will keep your water very clean for a long time.

But that doesn’t completely preclude water changes, either.

While theoretically, you could run a tank like this (if it balanced properly) indefinitely without water changes, and only adding extra water to make up for evaporation, it’s far more likely you will still need to do a water change at least once a month, if not more to make sure you don’t run into problems.

But, By using the right types of plants, and your tank is packed full of life this isn’t a big deal either. Often times you’ll find most of the water will need to be changed at once instead of in small amounts throughout the month because all that plant growth uses up almost everything quickly.

As far as I’m aware this is the best way to keep goldfish without filters…

Do keep in mind you will also need to take care of the plants and everything else in the tank as well. That means feeding the plants with fertilizers, and possibly C02. It also means adding additional food for the rest of the life in the tank if they need it.

So with that said, There is still the first option, Getting a filter. So what filter should I get? Chemical filtration, mechanical filtration etc?

There are a ton of options for filtration. My personal recommendation is simple sponge filters and air stone filters. It’s cheap, easy to clean and maintain, and reasonably good for a goldfish tank.

And if you set it upright, and grow moss and other plants inside the sponge filters itself, You can even bypass the need to clean it at all.

There will still be space for beneficial bacteria to do their thing, But at the same time, you will have plants that are eating up the solid and larger particulates that happen to get stuck to the filter itself.

And, even if you don’t do that, the procedure to clean it is to simply lift it out, squeeze it a few times in a bucket full of used aquarium water, and putting it back in every 6 months. Not a big deal!

But, if you are not a fan of such an easy filter, You have the other traditional options, such as HOB filters, Canister filters, and even central filtration systems. If you have one of those types already I see no reason not to reuse them for a goldfish tank if they work well.

They all serve their own purposes, be it biological filter, mechanical filtration, or chemical filtration.

What’s the difference? well…

Biological filtration is the most common in aquariums. It’s normally found in HOB filters, or Canister filters, which are generally filled with some sort of ceramic media that has space for bacteria to colonize. The benefit of this is that it removes many types of matter from the water, But tends to be less efficient than other methods so must be cleaned regularly.

Chemical filtration is any type of filter that uses chemicals to remove things from the water. This can be activated charcoal which you’ll commonly find in hang-on back filters and canister filters alike because it’s reasonably cheap and very effective at removing organic compounds like medications/ammonia etc… And lastly, there is mechanical filtration which is usually the form of a sponge or similar type of other filters that simply traps particles in the water column.

So in the end, Goldfish tend to do better in clean filtered water with goldfish filters or other types of filters as opposed to dirty water. It’s also easier to keep tank water and tank clean from solid particles, solid waste, and other things that make poor water quality with a filtration system in place. Be it sponge filters, mechanical filtration, air pump filters, biological filters, chemical filtration, or even undergravel filter. So many options to choose from for external filters and internal filters when fish keeping.

The live plant’s option is also good as it keeps out toxic chemicals, keeps the nitrogen cycle in check, and makes use of uneaten food, Trap solid particles. Aquatic plants certainly remove the need for external filters and promoted goldfish health, and with a bit of proper care, a proper cycle of good bacteria, your goldfish will live a long and healthy life rather than a short one that’s usually the case with messy fish.

Keep in mind if you use an airstone that gas exchange is happening. As you add oxygen into the water column you’re pushing out C02 which plants like to breathe. Having an oxygen stone isn’t necessary in a very planted tank and your better off with a filter that pull water in but doesn’t break the surface in that case. Breaking the surface will also push out the c02.


Owner of and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!