Goldfish Hole In The Head Disease (How To Save Your Fish!)

Last Updated on 2023-05-24

Goldfish may seem like a reasonably easy pet to take care of; however, much like with other pets, it depends on how knowledgeable you are about them, which ensures their wellbeing.

Goldfish are susceptible to disease, infections, and parasites, much like any other fish. The more we know the risks that come with our pets, the better we can put measures in to prevent anything bad from happening.

In this article, we are going to explore the disease ‘Hole in the head’ or Hexamita. We will explore how goldfish get it, the symptoms, treatment, and prevention techniques to stop it from happening to your pet, or if it does, how we can combat this disease!

What Is Hole In The Head?

Firstly we need to establish exactly what a hole in the head is.

Hole in the head disease, or Hexamita as it is also known, is a possible parasitic disease that affects fish with lowered immune systems or that live in bad conditions, making them susceptible to it.

It is said to be a parasite that lives in a fish’s intestines already but at very low levels. However, when water conditions worsen for our fish, this parasite is then able to multiply and have a seriously harmful effect on them. As the parasite multiplies, it spreads to the fish’s organs and slowly kills it.

However, this is just one theory of what it is. Others have suggested that it can also be a bacterial infection, nutritional deficiency, or even an environmental issue. So we can’t be quite sure, although we do know that it greatly affects fish in a bad environment and is limited to freshwater fish only.

Now we want to know exactly what factors contribute to hole in the head disease for your pet goldfish.

What Causes Hole In The Head In Goldfish?

The hole in the head is caused by goldfish living in very bad conditions, so in order to prevent or treat it, we need to look at the living conditions of your goldfish.

The causes include:

  • Bad quality of water
  • Stress due to wrong pH levels or temperature
  • Stress because of other fish
  • A bad diet, so can be lacking certain nutrients
  • A poor immune system which is exacerbated by bad environment

We can defeat these bad conditions by doing regular checks and cleaning of our tanks, which we will go on to explain later. We also want to combat it when we first get goldfish, as we don’t know what the conditions were like, where they have come from and whether they have a lowered immune system.

What Are The Symptoms Of Hole In The Head?

To ensure we can accurately treat our goldfish, we must first recognize the symptoms of the disease so we can identify it quickly.

These include:

  • Producing white, stringy faeces
  • Sores or lesions on the goldfish’s head or fins which will eventually produce mucus
  • Indents or holes around the head or eyes
  • Loss of appetite
  • Discolouration
  • Lethargism
  • The goldfish’s slime coating will begin to come away from its body

If your goldfish is showing any of these symptoms, it could well be the hole in the head disease, so we want to know how to effectively treat it.

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How Do You Treat Hole In The Head In Goldfish?

To treat the hole in the head disease, we first want to remove the goldfish from the tank that it is currently in. When transferring the goldfish to a new tank, we need to make sure that this secondary tank has perfect conditions for it to thrive in.

If your goldfish is able to eat, then you can feed it certain medications that will combat the disease; however, if not, you may find that you need antibiotics to clear it.

We constantly need to bear in mind how this will also affect the water quality, so regular checks of the secondary tank are necessary; otherwise, the treatment will be pointless. Anything that we add to the tank that is not part of our goldfish’s natural environment will affect the water quality, so we must continuously keep this in mind.

After the routine medication is administered, we want to ensure that the primary tank is also in the best conditions possible. This means that in the future, we may need to consider upping our checks or water changes to refrain from having these problems again. If the water quality is the problem, then we must put in more effort to rectify this problem.

After having been administered medications or previously having an infection or disease, our goldfish’s immune system will be lowered, which makes another bout of sickness easier to attain. This is why the living conditions for our goldfish are so important.

How Do You Prevent Hole In The Head?

This disease can easily be prevented as long as we know how to care for our goldfish properly. The following factors can greatly decrease the risks and ensure the best environment for your goldfish.


When first getting your goldfish, whether you think they are healthy or not, it is always best to quarantine them from the rest of your tank for around two weeks.

We recommend this because we do not know the conditions your goldfish has come from. Although the aquatic store you have bought your fish from may seem very clean, fish are renowned for carrying parasites. By quarantining them for two weeks, it enables us to keep an eye on any symptoms that may develop when we first own them.

We do not want to infect our tanks right when we feel we have set them up in the perfect conditions. By quarantining our fish, if any symptoms do appear, we want to treat them as quickly as possible, so we can then put our goldfish in our main tank.

We also recommend not adding pet shop water to your tank. This is because we do not know what parasites or bacteria may already be in that water, so we want to keep our own water fresh and treated at the optimum quality.

Water Quality

Even without the risk of parasites, disease, or infection, water quality is so important for your goldfish’s wellbeing. So here we provide some points to enable us to ensure your water is at the best quality it can be:

  • pH level – Goldfish require a neutral pH level of between 7.2 to 7.8. We want to monitor this level and keep it consistent as any sudden changes may be detrimental to your goldfish’s immune system. Goldfish are freshwater fish, so will thrive best between these levels and avoid them becoming sick.
  • Temperature – The ideal temperature for your goldfish tank will be between 20-23 degrees celsius. Any lower than this temperature range, and your fish will become lethargic as they rely on you to regulate their temperature as they cannot. Any higher than this and you may notice your goldfish becoming overly energetic, which is bad as in warmer temperatures oxygen levels are lower, which will again make them stressed and can lead to death. This temperature range is fundamental for your goldfish’s oxygen levels and will help reduce any problems with their immune systems.
  • Plants – We need to be careful what plants we are putting into our goldfish tanks, as they can affect the water quality. We need plants like Java Ferns, Anubias, Cabomba or Pennywort/Hornwort, which will not affect the water’s purity, as goldfish are already what we consider a ‘dirty fish’, due to the amount of waste they produce.
  • Tank size – The size of the tank is important also due to how much waste your goldfish produces. Goldfish need around 40 gallons of water for the first one, and 20 gallons of water thereafter. Any lower than this and your goldfish is essentially just swimming in its own waste, and you will need to clean your tank more thoroughly and regularly. A small tank can also lead to stress, which will affect your goldfish’s immune system, making it susceptible to disease.
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Water Changes

Water changes need to be consistent and done properly to ensure that your water remains of good quality.

We achieve this by doing a 20 percent water change every 7-10 days. We want all of the new water to be at the right temperature and pH level, so your fish benefit from it. However, if you find that your water is not of the best quality, you may want to up the percentages, which also may correlate with the size of your tank.

Water changes are fundamental for clean water, so if you are thinking of investing in a bigger tank, you may want to speak to an aquatic expert where you buy your equipment to know the best frequency and percentage of the water change. Although, for your first two goldfish of 60 gallons of water, a 20 percent change will be suitable.


We eliminate the amount of stress that our goldfish feels by ensuring that :

  • the fish tank is big enough,
  • they have enough food or the right amount of food
  • Other fish in the tank match their temperaments
  • They do not endure any sudden changes of temperature or pH level
  • Their tank remains clean

As long as we reduce the risk of stress for our goldfish, then we reduce their chances of any diseases. Just like with ourselves, stress levels can increase the risk of your goldfish becoming sick, so we want to keep a calm and consistent environment.


Goldfish are omnivores that require a well-balanced diet. Goldfish can taste and smell their food just like we can and are also liable to get bored of the same things all the time!

We want to stick to foods that have good nutritional value for them, so foods such as flakes and pellets that are designed for them, whilst also foods like peas, bloodworms, duckweed, brine shrimp, and any leafy greens are great for goldfish.

A well-balanced diet means the goldfish is less likely to suffer any deficiencies, therefore preventing any negative impact on their immune systems.

Existing Infection, Parasites Or A Lowered Immune System

We may not know about any issues before we buy our goldfish. We like to hope that we will be informed of any previous issues, but that is not always the case. This means that quarantining and keeping up with the other preventions is necessary for your fish’s wellbeing. A lowered immune system runs the risk of sickness right away, without us having anything to do with it.

By maintaining all these preventatives, we can ensure that everything we are doing is to the best of our abilities to keep our fish happy. However, we want to know if this particular disease is contagious?

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Is Hole In The Head Contagious?

Although researchers are not exactly sure what type of disease hole in the head is or its exact causes, we can identify that it is not necessarily contagious.

With that being said, we know the basic reasons why your fish may contract this disease, and it is detrimental to the tank environment and diet. If you have one fish that has contracted it due to poor water quality or incorrect diet or temperature etc., we can be sure that it is having an effect on the other fish in the tank.

If you do have a community tank and are facing this issue, then the other fish may not develop hole in the head disease, but poor living conditions for your fish may cause an abundance of other issues or sickness.

Is Hole In The Head Fatal?

The fatality of the hole in the head disease primarily correlates to how quickly you pick up on the disease in the first place.

In some cases, no, it is not fatal as you can identify the issues within your tank, such as poor water quality, and then put in procedures to change it.

However, if you do not identify the issue, then yes, this disease, like many others, can be fatal. You want to make sure that you catch it in the early stages, so your goldfish does not face any lesions or sicknesses that have progressed to the point that you cannot save it.

If you do realize that your goldfish has this particular disease, then you really want to identify how much effort you are putting in to create the proper environment or diet for your goldfish. There can be other issues from previous tanks; however, with the right treatment or knowledge of what to do in the case of this disease, you should be able to eradicate it.


So we now know that when acquiring goldfish as pets, there is a fair amount of upkeep with them. Prevention is key for goldfish, and we maintain this by ensuring that they are quarantined when we first get them; we keep their tank clean and the water quality good whilst also providing them with a well-balanced diet.

As long as we can deal with the upkeep on these few things, we should find that we have happy, healthy goldfish free from diseases such as a hole in the head!

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