Why Does My Goldfish Have White Spots (And How To Cure Them)?

White spots on a goldfish are symptoms of a disease called Ichthyophthirius multifiliis, which is often shortened to Ich. Ich is a highly contagious disease that can spread to other fish in your tank if left untreated. A serious case of Ich can kill a goldfish.

Eating Daphnia
Eating Daphnia

Goldfish have been kept as pets for centuries. Over many, many years, goldfish have been selectively bred from what we refer to today as a ‘common goldfish’ into the magnificent selection of body shapes and fin types now available to hobbyists.

I have been keeping fancy goldfish for 20 years or more, and over that time I have kept many different varieties. I am a massive fan of Oranda and Ranchu goldfish. Unfortunately, I do occasionally get a goldfish who is sick, and white spots are a fairly common problem.

Why Do My Goldfish Have White Spots?

Goldfish are generally hardy fish that can easily live for 20 years or more. They don’t often succumb to diseases, but when they do it can be serious. Sadly, Ich, or Ichthyophthirius multifiliis to give it its scientific name, is fairly common in goldfish which are stressed or have had their immune systems compromised.

The white spots you see on your goldfish are actually cysts caused when the parasite burrows into the goldfish’s skin. At first, you may only see one or two white spots, and a goldfish can generally cope with just one or two spots. However, Ich spreads rapidly in an aquarium and, if left untreated, one or two spots can quickly multiply until the goldfish is covered in them.

A few years ago I was given a small fancy goldfish, and I was too lazy to quarantine it. It came from a friend who had dozens of tanks, so I didn’t worry too much. Unfortunately, the little fellow already had Ich, which quickly took hold of my tank. Luckily, as soon as I realized I treated the whole tank and I didn’t lose any fish.



What Is Ich?

The white spots we see aren’t actually the parasite itself, rather they are cysts caused by the goldfish’s own immune system.

The cysts are the goldfish’s immune system reacting to the parasite that has burrowed into its skin. Once under the goldfish’s skin, the parasite will spend several days feasting on the goldfish’s blood. When it is ready, the parasite will drop off the goldfish and sink to the bottom of the aquarium where it will stay for a couple of days before dividing into hundreds of baby Ich parasites known as ‘tomites’.

Once hatched, each of these tomites go in search of a new host.

What Are The Symptoms Of Ich In Goldfish

There are two main symptoms of Ich in goldfish. They are;

  • White spots on the goldfish’s body
  • Goldfish rubbing itself again rocks, decorations, or the aquarium’s substrate

White spots

In the early stages of an outbreak of Ich, a goldfish may only have a couple of spots. These white spots look like grains of sand or salt. At first, the spots can go unnoticed, especially on larger, white goldfish. However, the number of spots can multiply rapidly.

Rubbing against rocks and decorations

Researchers believe that Ich cysts may be itchy to the fish. They have described the feeling as possibly being like a mosquito bite on a human. By rubbing itself against items in the aquarium, the goldfish may be trying to relieve itself of the itchiness the cysts cause or actively trying to knock the cysts off.

How To Treat Goldfish With Ich

Luckily for us hobbyists, there are a number of good treatments for Ich available. I have always had good luck using Ich-X which is made by Hikari. I follow the instructions on the packet which are, add 5ml of Ich-X for every 10 gallons (38 liters) of aquarium water.

If you are based in Europe, eSHa 2000 is a recognized treatment that is extremely effective.

One important note on treating Ich, the parasite is only vulnerable to treatment when it is in the ‘floating tomite’ stage. Once burrowed into the fish, chemicals will not treat it.

Bearing this in mind, a goldfish aquarium may need treating more than once to get all of the parasites.

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Treating Goldfish For Ich Without Using Chemicals

Quite often people are against using chemicals in their goldfish aquariums, or maybe they are located somewhere where suitable treatments are not available. In these circumstances, you will need to treat Ich differently.

Treating Ich without chemicals requires a two-pronged attack. Firstly, the temperature in the aquarium should be raised. Although goldfish don’t like their water to be really warm, it won’t hurt them if it is just for a few days.

Increase the water temperature to between 80°F and 82°F (26°C and 28°C). This increase in temperature speeds up the Ich parasites’ life cycle, meaning it spends less time under the goldfish’s skin and more time in the water column.

Once the temperature has been increased, gravel vacuum your aquarium thoroughly every day for 7 to 10 days. By gravel vacuuming, you remove the parasite when it is in the substrate multiplying into more parasites.

A word of caution: If you use this method to treat for Ich, you MUST NOT miss a single day of gravel vacuuming otherwise you may miss one of the parasites, and it only takes one parasite for the process to start all over again!

How To Prevent Goldfish Getting Ich

As with so many goldfish problems, prevention is better than cure. In theory, preventing Ich from ever getting into a goldfish aquarium should be fairly simple, providing we follow some basic rules.

  1. Quarantine all new goldfish for at least two weeks prior to adding them to the aquarium
  2. When in quarantine, treat with Ich-X as a precaution
  3. Maintain good water quality in the goldfish tank
  4. Feed goldfish good quality food
  5. Gravel vacuum goldfish tank on a regular basis as a precaution

Ich is prevalent in the aquarium hobby and we should assume all new fish have it. By quarantining our new goldfish we seriously reduce the chances of Ich entering our aquariums.

In Conclusion

The vast majority of the time that a goldfish has white spots, Ich is the culprit. When you see the first signs of Ich, treat with a good quality Ich treatment, gravel vacuum your aquarium substrate, and carry out regular water changes in your aquarium.

If you tackle Ich quickly, it is perfectly curable and there is no reason any goldfish should


About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James
Editor