What Fish Put out the Most Waste in an Aquarium?

People love to keep aquariums inside their homes because they are an aesthetically pleasing addition to the interior design of a house.

However, before you bring an aquarium into your home, you must first know that it comes with its fair share of responsibilities. After all, a dirty aquarium is highly unpleasant to look at.

This is why you must take out time from your busy routine to keep your aquarium clean and well-maintained.

This will also help in keeping your fish healthy and happy to ensure they live a long life.

Here’s a list of fish that put out the most waste in an aquarium. Avoid putting the fish mentioned below in your aquarium to ensure that you can keep the aquarium clean far more easily.

Fish that Put Out the Most Waste in an Aquarium

Choosing the right type of fish to put inside your aquarium plays a huge role in determining the kind of cleaning and maintenance it will require.

Some species of fish are very helpful in keeping an aquarium clean.

They are useful because they eat up any small bits of leftover food or algae in the aquarium.

On the other hand, there are some species of fish that are messy and produce a lot of waste. This makes it harder to keep the aquarium water clean.

As a result, your aquarium requires heavy filtration and regular cleaning to look clean.

Below is a list of fish that put out the most waste in an aquarium.

The Oscar

The Oscar is a member of the cichlid family of fish. It is a fish that has big beautiful eyes and this often allures people into taking them home for their aquariums.

Oscar fish

Besides their beauty, the predatory nature of an Oscar is also a reason why people like to put this fish in their aquariums.

Oscars have an aggressive personalities.

Many people enjoy watching this fish display its natural aggression. However, most people are unaware of the drawbacks of keeping Oscars in their aquariums.

Due to their have a predatory nature, Oscar fish are messy and excessively feed on smaller fish.

This is why they end up putting out more waste than other fish.

Moreover, the nitrates in the waste of an Oscar fish make the water inside an aquarium toxic.

This way, the water inside the aquarium quickly becomes unhealthy for Oscars as well as other fish.

As a result, you have to change the water inside your aquarium more regularly if you want to keep your pets healthy.

Weekly water changes are recommended for an aquarium when you have an Oscar fish inside it.

Otherwise, the poor quality of water can easily lead to the hole-in-the-head disease which the Oscar fish is highly susceptible to.

Furthermore, an adult Oscar can grow up to eighteen inches long. They are big in size and also quite messy so they require bigger tanks and at least 55 gallons for healthy living.

A bigger aquarium means the task of changing its water becomes even more time-consuming.

The Pleco

The next species of fish that we don’t recommend housing inside your aquarium is Plecos.

Common Pleco

Many fish store employees recommend people to buy Plecos because they eat the algae growing inside their aquariums.

However, while it is true that the Pleco fish will nibble on algae inside your aquarium, they will also destroy the water quality.

As they grow in size, they start to eat more and more and begin to produce a large amount of waste inside the aquarium.

As a result, you can never afford to be inconsistent in your cleaning schedule if you plan to keep Pleco fish inside your aquarium.

Plecos are considered to be one of the most waste-producing fish species. They quickly ruin the water quality inside an aquarium by pooping.

This is why many people have gone as far as labeling them as “pooping machines.”.

So, beware and avoid putting Plecos inside your aquarium if you want a clean aquarium.

Moreover, once fully grown, a Pleco needs a minimum of ninety gallons of aquarium water.

This requirement means changing the water inside your aquarium will definitely be a hassle.

The Goldfish

Another type of fish that puts a lot of waste in an aquarium is goldfish. The goldfish is one of the most commonly kept fish in an aquarium because of its bright orange appearance.

Pearlscale Goldfish

They instantly light up a dull aquarium but this vibrancy comes with its drawbacks.

The main problem with keeping goldfish inside an aquarium is that they are extremely messy but still require clean water for healthy living.

They put out a lot of waste because they leave leftovers of their food to rot in the aquarium.

This means you need an efficient water filter inside your aquarium for getting rid of these impurities.

You will also have to change the water regularly to keep your goldfish fit and healthy. Most shop owners suggest changing at least 25% of the aquarium water on a weekly basis.

Moreover, goldfish also need a higher amount of oxygen in the water tank than most other fish.

This means you must have a powerful filtration system and an adequate supply of oxygen inside your aquarium if you want to keep goldfish as pets.

The Clown Loach

Although many websites online try to warn against buying the clown loach if you are beginner aquarists, people still tend to buy them a lot.

Clown Loach

People are attracted to buying the clown loach species of fish because they are very social and playful.

They are often observed chasing each other inside the aquarium so it’s very interesting to watch them.

One drawback of keeping clown loaches inside your aquarium — besides the mess that they create —is that they are social animals so they need to be kept in at least a group of five.

This means your aquarium must have a minimum of 80 gallons of water and needs heavy filtration to stay clean.

Clown loaches are highly sensitive to dirty waters so keeping your aquarium clean is essential for their health.

Common Types of Waste inside an Aquarium

Now that we’ve highlighted the fish that put out the most waste in an aquarium, we also want to discuss the different types of waste inside an aquarium.

Keeping the aquarium clean is the responsibility of every aquarist and it shows how concerned you are with your pet’s health and overall wellbeing.

Solid Waste

Metabolic waste excreted by fish and leftover bits of food can easily cause unpleasant smells inside the aquarium.

If you often observe uneaten bits of food inside your aquarium, then this is a clear sign that you are overfeeding your fish.

This is why you need a powerful filter to help you remove most solid waste from the aquarium water.

Microscopic Waste

The uneaten bits of food will also provide nourishment for nitrates, ammonia, and nitrites inside your aquarium. These are toxic chemicals and are harmful to your fish.

Ammonia and nitrites are considered to be awfully dangerous whereas nitrates are a little less toxic.

This is why you need to remove these harmful chemicals from the aquarium water.

You can use test strips to inspect the levels of ammonia, nitrites, and nitrates in the water inside your aquarium.

If the levels are high, you can use simple products like Aqua Safe, Stress Coat, or Amquel to remove these chemicals.

Moreover, you should also clean and replace the cartridge of your filter to make sure it is functioning properly.


The next type of waste you should always avoid having in your aquarium is algae.

The presence of Algae interferes with homeostasis and also ruins the aesthetic appeal of your aquarium.

We recommend using an aquarium scraper to get rid of the algae on the glass tank.

If you notice algae on the décor inside the aquarium, then you should simply take them out from the water tank and wash them with hot water.

Never use detergent as that can allow harmful chemicals to enter the water inside your tank.

Algae growing on plants inside an aquarium can be cleaned by wiping them with a linen cloth.

This way, bits of the algae will float in the water which will be removed by the filter in a few hours.

Also read: How to Get Rid of Black Algae in a Fish Tank?

Last Few Words

Fish are highly popular pets all around the world for good reason. Watching fish swim in an aquarium is considered to be soothing and helps lower anxiety.

Their beauty and peaceful nature also make them an ideal choice of pet for people who don’t want the additional responsibility of walking or playing with a pet.

That said, you must take a number of factors into consideration when selecting the fish for your aquarium if you want to keep it clean.

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