Will Fish Die in an Aquarium Without a Filter?

Yes. Ok, now let’s address why – 2 main reasons: Waste and Oxygen. Let’s first address the oxygen issue. Marine species that have gills absorb oxygen from the water with their gills. Water that is stagnant or has little to no agitation, usually is oxygen deficient. Your aquarium without a filter will not allow for a healthy amount of oxygen to be present nor will there be a source for replenishing the oxygen in the water of your aquarium. The filter creates movement in the water which in turn agitates it. However, not all filters break the surface of the water which is why aeration of some kind is necessary in addition to the filtration system.

Now let’s address the waste issue. Without a filtration system, the waste in your aquarium cannot break down nor will it be removed. This will not create a favorable outcome for your aquarium’s inhabitants. They all require a clean environment free of harmful waste, just as you or I do. So now that we have answered that question, let’s talk a bit about the type of filtration that a healthy aquarium should have.

There are 3 main types of filtration:

  • Biological
  • Mechanical
  • Chemical

They each provide a unique element to the aquarium and keep it in a thriving state for it’s inhabitants. Let’s take a look at each type’s individual benefits.

Biological Filtration

This type of filter houses beneficial bacteria which helps to break down waste and as a result ensures water quality. The main effective type of biological filtration in my opinion is the canister filter. I currently have 2 – 1 on my shark pond and 1 on my mostly fancy tail guppy tank. Right now I am using the Marineland Canister Filters – more specifically the Marineland PC-ML530 Multi-Stage Canister Filter on my 300 gallon shark pond and a Marineland Magniflow Canister Filter 220 GPH on my 40 gallon freshwater – mostly fancy tail guppy – aquarium.

I have also used Ehiem’s canister filters in the past and I really like that brand as well.

What they do is add a lot of surface area with their contents which is filter media. This provides a home for the beneficial bacteria and allows the water to pass through their “home” so that they can help to break down the waste in the water column of the aquarium. Depending on the number of gallons that your aquarium can hold and how often you need the water to be passed through the filter per hour will determine the right canister filter for your aquarium’s needs. It will also depend on the species that you are going to keep as some require more or less flow than others.

Mechanical Filtration

This type of filtration sometimes comes with a “bio-wheel”. This is not enough of a biological filtration method in most cases. So if your hang on filter/mechanical filter has one of these, I still recommend a canister filter for biological filtration purposes in addition to the mechanical filtration. I usually remove the bio-wheels to be honest. So mechanical filtration removes pieces of debris from the water column of your aquarium. They either come with pads or cartridges of some kind which you will need to change out on a schedule in order to ensure that the filter can do it’s job properly. While canister filters do contain some form of a mechanical filtration pad or a filter floss type of material, I recommend removing them and using that area or tray for more biological filtration media. The hang on filters are the best for mechanical filtration in my opinion.

Here are what most hang on mechanical filters look like:

Depending on how many gallons your aquarium is (how many gallons it can hold) will determine what size mechanical filter you will need.

Chemical Filtration

Carbon, Puriagen, ChemiPure, etc. all of these are examples of chemical filtration. The most common of them all is carbon. This helps to maintain water quality by dissolving impurities in the water caused by waste. There are a lot of different types of carbons and resins to choose from. The best place to start is pure carbon and do your research from there. It’s important to change out the carbon or resin regularly. This will depend on the recommendations for each product.

So not only do fish need a filter in an aquarium, in order to thrive, they need 3 different kinds of filters/filtration.

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