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How To Treat White Film On A Goldfish!

With goldfish being the most commonly kept species of fish in the world, we constantly see a wide range of questions about caring for goldfish from people new to the fish keeping hobby.

These questions really can cover a wide range of different topics due to beginners having to learn so much so quickly but one question that we have seen being asked recently is about a white film on a goldfish forming.

The three most common causes of a white film forming on your goldfish are due to a fungal infection of various types, a columnaris bacterial infection, and ammonia burns.

There are also a number of far less common reasons that a goldfish may develop a white film but the vast majority of people will find that they have a white film on their goldfish due to one of those three main causes.

Thankfully, in many situations, a white film covering a goldfish is very easy to treat and most goldfish will make a full recovery with minimal issues but there is usually some confusion on the condition with many people making easy to avoid mistakes.

Due to this, we have decided to publish this article going over the topic in great detail to try and help as many of our readers as possible who have a goldfish covered in a white film get their fish back to full health as quickly as possible.

Is White Film On A Goldfish Just Their Natural Slime?

It is rare that a white film covering a healthy goldfish will be their natural slime and a white film on a goldfish is almost always due to a potential problem with the fish.

Things such as a poor diet or old age can cause the production of the natural slime on a goldfish to perform poorly but even then, it is rare that the slime will be a white color.

We know that there are a number of posts on social media saying that white film on a goldfish can be natural but this posts are incorrect and should never be followed as it can put your goldfish and the other fish in your tank at risk.

Why Does My Fish Have White Slime?

The three most common causes of a white film covering a goldfish are as follows:-

  • Fungal Infections
  • Columnaris
  • Ammonia Burn

The majority of the time, people will end up finding that they have problems with a fungal infection in their aquarium but Columnaris is still surprisingly popular with ammonia burns usually being the least common of the three main causes.

Fungal Infections

Fungal infections are very common in aquariums and even experienced fish keepers end up having problems with relatively frequent breakouts of fungus in their tanks.

It is easy for a single fungal spore to get into an aquarium and due to most aquarium setups offering perfect conditions for the fungus, the spore rapidly duplicates and then before you realize it, you have a full blown infection in your tank.

As we covered in our article on white slime on aquarium wood and white slime in a fish tank, there are a number of different types of fungus that can take hold of your aquarium and cause issues with a white fuzz, a white slime or a white film forming on your goldfish.

Thankfully, in most cases, these fungal infections can quickly and easily be treat with cheap and easy to find products such as Pimafix with most fungal infections being treat within a week and your goldfish being visible better within two weeks.

As with all problems within the fish keeping hobby, the longer you wait to take action to treat a fungal infection, the more difficult it can be to treat it so if you suspect that this is your issue, start a suitable treatment as quickly as possible.


Columnaris is far rarer than fungal infections with Columnaris being a type of bacterial infection that can quickly take hold of your goldfish and cause a white film to form on its scales.

In most cases, Columnaris is accidentally added to your aquarium when you add new rocks, plants, substrate, fish or live food.

As we covered in our article on why betta fish turn white, the number of people having issues with Columnaris is slowly increasing due to more and more people keeping live plants and rocks in their tanks allowing the bacteria to get into their tanks.

Thankfully though, if you catch Columnaris early enough, it is very easy to fix.

In our opinion, the best way to quickly and easily treat Columnaris for cheap is to use Melafix and Pimafix in your aquarium at the same time.

Both products use different active ingredients with the Bay Tree extract from Pimafix and the Tea Tree extract from the Melafix having a compounding effect with each other to treat Columnaris as quickly and easily as possible.

Alternatively, you can also use API Fin And Body Cure but this does tend to be a slower treatment and the longer the Columnaris is affecting your goldfish, the less likely it is to make a full recovery.

Ammonia Burn

Ammonia burns are the least common cause of a white film forming on your goldfish and these are usually very easy to prevent but once the chemical burn has affected your goldfish, the scarring can be permanent.

A white film is not the only symptom of ammonia burns and it is not guaranteed either with a number of other symptoms often being more common.

You can confirm if this may be the problem in your tank by using a water test kit to check the ammonia levels in your tank.

If the ammonia levels are too high then there is a chance that the ammonia in your tank is causing chemical burns to your goldfish with the white film being a symptom of this.

Other potential signs of the ammonia cycle in your tank being the issue is that your goldfish may have red gills due to the irritation being caused by the ammonia burning the fish.

We always recommend that our readers implement a partial water change strategy with their aquariums where they change between 15% and 25% of their tank’s water once per week.

In most cases, this will be enough to keep the ammonia cycle in check in your aquarium and prevent the ammonia levels in your tank from getting high enough to cause these chemical burns.

As we mentioned earlier in the article though, once these chemical burns have affected your goldfish, the chances of them fading are minimal and long term scaring can often be left over.

The white film on your goldfish will usually stop forming once the ammonia levels in your tank have been dealt with though.

What Does A Fungal Infection Look Like On A Goldfish?

With fungal infections being the most common cause of a white film covering goldfish, we just want to quickly go over how you are able to better identify this as the issue.

In most cases, the white film that is covering your goldfish will have a slight fur texture to it if you look closely at your goldfish where as the white film caused by Columnaris or ammonia burns is usually smooth.

You may also notice the goldfish slime coat peeling off too where as it will usually stay on the fish longer if the white slime is due to Columnaris or ammonia burns.

How Do You Treat White Slime On Goldfish?

As we mentioned earlier in the article, each of the three most common causes of a goldfish having problems with white slime forming on its scales has their own unique treatments specific to that condition.

If our goldfish is developing a white film or slime due to a fungal infection then Pimafix is our recommended treatment of choice and following the dosing instructions on the label should deal with the fungal infection quickly.

If you think that your goldfish are developing a white slime or film due to Columnaris then we would recommend that you use Melafix and Pimafix together to get the best of both worlds as the active ingredients in both products really work well together against Columnaris.

Ammonia burns can usually be prevented with regular water changes to keep the ammonia levels in your goldfish tank in order but once the chemical burns have taken hold, the scarring is usually permanent on your fish.

How Do I Stop White Slime From Affecting My Goldfish In The Future?

In reality, it is very difficult to totally protect your goldfish from having issues with white slime in the future due to fungal spores and the Columnaris bacteria usually being accidentally added to your tank.

You can keep new fish additions to a minimum as well as avoid adding any new live plants, rocks or substrate but this is not realistic for most people.

Our advice would be to try and set up a quarantine tank if possible where you will hold new additions to your tank for a week or so to wait and see if you end up seeing any signs of Columnaris or fungal infections in your quarantine tank before you add the new addition to your main tank.

If you are having issues with ammonia burns irritating your goldfish and causing a white film to form then a weekly water change of between 15% and 25% should easily be enough to prevent the issue from happening in the future.

There are a number of different test kits on the market that you are able to use to monitor the build up of your ammonia levels in your tank too giving you plenty of warning of any potential issues well before they occur and get to risky levels.

Should I Be Worried If There Is White Slime On My Goldfish?

All three of the more common causes of a white film or white slim forming on a goldfish can prove fatal if they are left unchecked and they will usually end up quickly taking hold of all fish in the tank too.

This is why it is so important that you try to deal with any potential problems in your goldfish tank as soon as you notice them as they are usually very easy to treat provided that you catch the condition early.

Still, if your goldfish is old or has other health problems, then the common causes of a white slime forming on the fish can still prove fatal to the fish even if you do everything right during the treatment process.

If you do have a goldfish that is more at risk, we would not recommend that you increase the doses of the treatments for the causes of the white film as increasing the doses of the treatments can end up causing problems and putting the fish at risk anyway.

Always follow the exact, easy to follow dosing instructions that are on the label of the product of your treatment of choice and be sure to stick to dosing your tank with the product for the recommended time frame in the recommended amount on the label!