What is Bioload? And Why is Bioload Important?

WFor my love of aquatic creatures, I never hesitate to add a new fish in my home aquarium.

But after last month, I put a stop to adding new fish in this tank when I found out that bioload inside the tank is affecting the health of my innocent pets.

Since I was not aware of this term bio-load when I first heard it from a friend, I decided to find out more about it.

So, what is bio-load and why is bio-load important? Bio-load refers to the waste materials of the aquarium water that has a negative impact on the overall water condition and fish’s health. The fish wastes, leftover food particles or decaying plants encourage bio-load, and it Is really necessary to control it if you want your fish to live a long life.

In this article, I have put together all the information I could gather about bio-load. I’d like to put light on the following points to give the readers a clear understanding of bio-load:

  • What is Bioload?
  • Source of Bioload in the aquarium
  • Start of bioload in the aquarium
  • Selecting a filter
  • How to determine the bioload of your fish tank?
  • Tips to control the bioload

What is Bioload?

The full form of Bioload is Biological load.

But the full term is only used in the papers, and you will commonly come across the former term in everyday life.

The experienced fish keepers do not need an introduction of this term ‘bioload.’

The aquarium water is full of impurities and dirt.

Bioload is the phrase that is used to refer all the wastes in your fish aquarium.

To understand the bio-load and its connection with the aquarium water, let’s find what actually exists inside the tank.

Besides fish, plants, and other tank accessories there are some bacteria found in the tank water.

All the living organisms secrete the waste materials from their body that pollutes the water. The waste materials are either solid eliminations, liquid or gases which are released inside the water.

Some of the waste materials are eliminated by the tank filter, but some of them require another filtration method.

In simple words:

The bioload is the aquarium water pollutants which put the life inside the aquarium at risk.

Source of Bioload in The Aquarium

So, have you thought where does all the waste in your aquarium come from?

Let’s find out below:

Besides snails, fish, shrimps, the aquarium has a lot of bacteria and microorganisms living in it. Of course, a human eye can not see these tiny organisms, but they contribute a big part in adding wastes to the water.

Please note that anything you put inside your aquarium can play a part in bioload production.

Following is a list of factors that produce prevalent kinds of bioload in the aquarium water:

  • Food particles
  • Fish Excrement
  • Respiration
  • Decaying plants

1: Food Particles

Uneaten food particles start decaying inside the water if not removed on time. Rotten food plays a big role in polluting the tank water.

Even if a little particle of stray food sticks at any corner of the tank and you miss taking it out, it either deteriorates or consumed by bacteria and other microorganisms in the tank.

These microorganisms release more wastes in water after consuming the leftover food.

2: Fish Excrement

The excretion of waste materials (poop) will always affect the water condition.

The waste materials and the secretions from the fish’s body make the water filthy. If the water is not changed regularly, then your fish can get sick or even die.

3: Respiration

Fish releases carbon dioxide as waste while breathing, if it is not converted into oxygen through the process of aeration, then this gas could be harmful to your fish’s health.

The fish also releases ammonia and other harmful bodily wastes.

4: Decaying Plants

Live plants could start decaying inside the tank water. Excessive algae and fungus make the water condition worsen. This is a threatening factor that increases the bioload in the tank water.

Start of Bioload in Water

Have you ever thought how the fish in wild deal with bioload?

Well, nature has its own way of dealing with bioload. In the natural habitat, the water keeps on flowing, so the wastes don’t accumulate at a place.

Coming back to your aquarium, as you know it is a limited space filled with a small amount of waste. So, no new water flows inside it.

However, a water filter can be installed inside the tank that helps in recycling the water.

But as it is an artificial setting, that is why we can never say that the filter could provide 100 percent clean water.

There is always the possibility of impure materials inside the water tank which could harm the fish’s health. The aquarium water is never fully clean, but at least it should be safe for the living.

It will not be wrong to say that inside an aquarium, the fish live with their own waste. Now, it depends on the efficiency of your filter that to what extent it can keep the water clean.

If the amount of wastes, i.e. bioload is high, then the filter will fail to clean the water.

Before getting a filter for your aquarium, you should consider the following things:

  • Number of fish
  • Live plants and other creature
  • Size of tank

Selecting a Filter

If you are planning to keep a large number of fish and live plants in a tank, then the filter should be bigger.

If you can not install a big filter in a small size aquarium, then you should avoid crowding the tank with a large number of fish and other creatures.

And another thing:

The waste materials release nitrates, nitrites, and ammonia into the tank that makes the water poisonous.

A good filter does not only trap the waste materials from water but also carry bacteria to process nitrites and ammonia.

If your filter fails to clean the water, then the waste will accumulate that leads to diseases and deaths among fish.

How to decide the filter for your tank?

The aquarium filter has to recycle the tank water to clean it before it goes back to the tank. Even if you change water on a regular basis, it needs to go through the filter to balance the water condition.

A filter can not completely deal with the bioload, but it helps in alleviating the bioload effect.

Following are the features of good aquarium filter:

  • It can remove chemicals, heavy metals, and other materials
  • It can remove odors, debris, and impurities
  • It has the tendency to neutralize or eliminate the harmful substances like ammonia, phosphates or nitrites
  • An efficient working in all sizes of aquarium
  • It has the 360-degree rotational system
  • It has a quiet & powerful motor
  • It has tight seals to prevent leakage

How to Determine The Bioload of Your Fish Tank?

There is no standard unit of measuring the bioload in an aquarium. Also, there is no instrument to determine the bioload of your fish tank.

Though normally, the amount of bioload depends on the fish’s

  • Size
  • Eating Nature
  • Digestive system

The big sized fish have bioload whereas the small ones have tiny bioload.

Getting to know the level of bioload is necessary because it helps you in maintaining the water quality. The ultimate goal is to minimize the bioload of your tank water so that your fish can live a happy life.

If the bioload is producing more waste than the system can handle, then it will disturb the nitrogen cycle leading to negative effects on the fish’s health inside the aquarium.

However, testing the bioload is relatively simple. The ammonia and nitrite level must be 0 ppm.

The bioload of your aquarium is increasing if the level of nitrates convert by bacteria in your filter is lower than the level of ammonia and nitrites.

If the bioload level increases then you have these option:

  • Reduce the number of fish inside the tank
  • Get a bigger sized filter
  • The other way is to get a new and big filter, but that can cost you a lot of money.

So, it is concluded that being a fish owner you need to observe the fish behaviour and tank conditions to determine the bioload. Only with experience, you will learn how to control the level of bioload by considering all the other cycles occurring in your tank.

Controlling bioload is essential in order to stop it from spreading all across the tank water and harming the fish.

If you notice something is wrong inside the aquarium, then it indicates the imbalanced nitrogen cycle. That means the level of nitrites and ammonia is rapidly increasing.


As soon as the nitrites and ammonia level goes up 0ppm, the bioload level exceeds.

So, be aware of the level of the chemical concentration of your tank water.

Tips to Control The Bioload

You can follow these tips to fight the challenge of bioload inside your aquarium:

  • Regular water check
  • Install an efficient filter
  • Avoid adding extra food
  • Filter maintenance
  • Reduce the number of fish
  • Increase the level of oxygen
  • Consistent water change
  • Regular water check: Keep on checking the level of nitrite, nitrate, and ammonia in the tank on a weekly basis
  • Install an efficient filter: Install a good filter that suits the tank size and number of fish inside the tank. The filter must work all day long to keep the water clean
  • Avoid adding extra food: It is not wise to add an extra amount of food, not only for water condition but also for the fish’s health. So, if you see any uneaten food in the tank water, remove it before it starts decaying
  • Filter maintenance: Check the filter for any blockages. Try to clean it as the dirt accumulates on the filter after a few days.
  • Reduce the number of fish: Reduce the number of inhabitants of the aquarium. It is the best way to stop the tank water from polluting.
    If you think that the tank size is too small for all the fish you are keeping the, do not wait for a second to eliminate some of the fish. It could be hard to let go of your pets, but it is for their own safety.
    In this way, the remaining fish will live a much healthier and happier life.
  • Increase the level of oxygen: Aeration can help in increasing the level of oxygen.
  • Regular water change: Some wastes are dissolved in the water and filter cannot take them out. The only option that is left is water change. The fresh and clean water retains more oxygen and has minimum bioload.

Related Questions

Can my aquarium filter kill the fish? Some powerful aquarium filter takes in the little and delicate fish. The fish may end up dying after getting stuck into the filter. The best way is to install the sponge filters inside the aquarium where small sized fish live or else cover the filter fan with a net.

Does a fish instantly die due to bioload? No, bioload doesn’t kill the fish instantly. In fact, the fish gets sick first due to bioload. The behaviour or eating pattern of fish change and the health of the fish fall eventually. You can save your fish from dying if you take out the fish from the polluted water as soon as you acknowledge the bioload.

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