How To Sanitize Fish Tank After Disease

How to Sanitize Fish Tank After Disease

Losing your fish after a disease outbreak can be a terrible loss and one that can be both expensive and depressing.

But, it is important to get over terrible events, learn from your ways, and discover when you need to do so that this does not happen again.

In this article, we will be looking at how you can sanitize your fish tank after disease has struck, as well as some of the reasons your tropical fish may have fallen ill.

Why Do Fish Get Sick?

Your aquarium fish will have gotten sick for a reason, certain factors can really impact your aquarium friends, and without them, there is very little chance of a disease outbreak happening.

Usually, the cause is because of the following reasons:

One of your fish or perhaps more is the host of this disease and has spread it to the rest of the aquarium.

Think of this fish as a carrier of sickness, and will be the origin of the disease affecting your aquarium.

Your fish could be stressed out for any number of reasons, but the following are the most common, extreme pH, water temperature, physical injuries, over-crowding, organics, ammonia, or nitrates.

You may have a pathogen like a fungus or a virus that has spread in the aquarium and caused your fish to get sick.

This can happen when a fish is weakened or stressed, essentially, the bacteria can attack the fish’s organs and skin.

This outbreak only happens when the organisms’ in the aquarium are unhealthy, if everything is balanced you should not have an issue with any pathogens.

In short, your fish should not be getting sick if they are in clean and stress-free environments, or you do not have a carrier spreading a disease.

But, you can never know for certain if a fish is stressed out until it is too late, so make sure you’re paying attention to your aquarium friends, so you avoid having a terrible disease outbreak.

How To Clean A Fish Tank After A Disease Outbreak

Sometimes the unthinkable happens, and you are now in a situation where you will need to sanitize your aquarium in order to make sure that there are no longer any traces of disease amongst your now healthy fish.

We have created a simple step-by-step process you can follow in order to achieve this.

Take Your Fish Out Of The Aquarium

The first and most obvious step for this job is to remove your fish from the aquarium you are about to clean.

You can put your fishy friends in a temporary tank while you work on disinfecting their homes.

Take Everything Out Of The Aquarium

This part can be difficult, especially if you just got all your plants to flourish and everything looks perfect.

But, you will need to remove everything, this will include:

  • Substrate
  • Rocks
  • Plants
  • Caves
  • Driftwood
  • Decorations
  • Filters
  • Lights
  • Pumps

Absolutely everything that is in your tank must come out and be sanitized.

Make sure to do a thorough job, as leaving things inside the tank while you clean could lead to a relapse and your fish may get sick again.

Start Cleaning

You will need a cleaning solution that is about 1 part bleach and 10 parts water, this is a really effective way to clean and disinfect your tank.

Using an algae scrubbing pad and the cleaning solution, you must clean the inside and outside of the aquarium walls.

After you are done, the next step is to rinse the aquarium thoroughly, this is because the bleach and chemicals you have just used can be detrimental to your fish.

The Filter

Your filter should be out of your aquarium, now is the time you should clean it.

If the disease was truly horrible, you will need to replace the media.

This is not ideal, but you will need to dispose of the biological, mechanical, and chemical media.

The downside of this is that by getting rid of the media, you will also get rid of the healthy bacteria that help your fish stay alive and healthy.

Cleaning your fish tank

But, because of the disease, you will be replacing the water and have to cycle the tank.

Regardless, you will need to use your bleach solution to clean as many of your filters as you can.

Make sure to rinse them thoroughly so that there is no residual bleach on anything.

Plants, Decorations, Rocks, And Lights

Everything will need to be wiped down and cleaned using your bleach cleaning solution.

When you are cleaning your lights, make sure to be careful as you can easily damage electrical components.

Make sure that your decorations, plants, and rocks are also cleaned using this same solution, all the while making sure that you rinse each item so that there is no bleach left on them.

Take Your Fish Out Of The Aquarium

Once everything is clean, and you have made sure that any item that could have come in contact with this disease has been sanitized by your bleach cleaning solution, you can start putting all of your components back into the tank.

Since you will need to cycle your tank, and you have changed the substrate, water, and filter media, the next step is to check your nitrogen cycle before you put your fish back in the tank.

If you do not have time to spend weeks doing the cycle, there is an easier way to speed up the process.

You can buy a bottle of beneficial bacteria and put it in your water, this should instantly cycle your aquarium.

As a side note, it might be a good idea to add fish medicine to the water, this should help stop the disease from reappearing.

This is only a good idea if you have an idea of what your disease was.

The treatment is great as a preventative and will get rid of any last remains of the disease in your surviving fish.


It is of the utmost importance that you take precautions to avoid your fish getting sick in the first place.

Making sure that you keep your tank clean and your fish healthy is a great place to start.

If tragedy strikes, and you do end up with a disease in your aquarium, you will need to take care to clean everything and replace the aforementioned items so that every trace of the disease is gone.

On that note, after you have cleaned the tank and all your fish are back in their homes, you will need to monitor the situation and take precautions to make sure that the sickness does not come back and cause chaos again.

Remember, your fish’s life and health are in your hands.

It is up to you to make sure that they live good and healthy lives.

With that in mind, that is all for this article, if your fish do happen to get sick, take it in your stride. Do your best and everything will come out right.

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