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Fish Tank Guides / Illness and Disease

Epistylis – Fish illness


Epistylis – Fish illness

Epistylis is a disease commonly found in aquarium fish. In many cases, it can easily be confused with White spot/Ich, or as a fungus, due to the visual effect it creates on the fish.

Epistylis is just as common in the aquarium as White spot and it most commonly occurs in new aquariums. But Epistylis is more deadly than White spot is.

Epistylis can be seen on the fish as small white ‘tufts’, often on the fins at first but it can quickly spread all over the body.

These immobile organisms attach themselves to the fish and can cause the fins and scales to erode. In large enough quantities, Epistylis is fatal but lucky for us it is treatable and even more easily preventable.


Diagnosing Epistylis

Epistylis appears as small white tufts on the fish, as these organisms are immobile, they usually first attach at places where the fish most comes into contact with other surfaces, such as the pectoral fins of catfish.

I’ve seen a lot of photos on social media where people immediately diagnose white spots on a fish as white spot disease.

This is totally understandable as the two often look very similar.

On appearance, these organisms may also look like a fungus and, because of this, Epistylis is often referred to as a false fungal infection.

It is actually quite difficult to distinguish by the naked eye between White spot, Epistylis and fungal infection.

The best ways to tell the difference are:

  • White spot/Ich usually appears as white dots no larger than a grain of salt. Epistylis will grow up slightly into the water column from the fish.
  • Epistylis often appears to be very white, Fungal infections are more grey in colour and sometimes brown.


Epistylis 2

(Photo Credit –


Treating Epistylis

Treating Epistylis is vital, as I mentioned, it is far more deadly than the dreaded White spot, infact, White spot probably gets a worse reputation than it deserves due to Epistylis being confused for it.

So how do we treat it?

Epistylis doesn’t feed on the fish itself, it feeds on bacteria, but it often causes bacteria and infection to attack the fish where it has damaged the scales/fins.

It’s a good idea to treat fish with medicated anti-biotic food, this will help to prevent any other infections, such as fin rot, from affecting the fish.

Anti-bacterial medications are a good idea too, as they will remove the food that the Epistylis feeds on and will help to protect the fish further from secondary infection.

To treat the Epistylis, Salt baths have been shown to have a really positive effect.

It is recommended that a salt bath of 5 level teaspoons for each litre of water is given to the affected fish daily for up to 10 minutes at a time, or until the fish loses buoyancy and rolls over.


You will also need to take the preventative measures listed below:



Preventing Epistylis

Preventing Epistylis is fairly easy, the organism feeds on bacteria, so keeping a clean, healthy aquarium is the key to preventing it.

A good maintenance routine is essential to keep your aquarium clean, but there are a few things to consider:



Filtration needs to be capable of keeping the aquarium clean, so your filter needs to be powerful enough, full of beneficial bacteria and well maintained.

If you have a new aquarium and a new filter, there is a good chance that there are no bacteria in the filter to keep your aquarium clean.

If that is the case, it is a good idea to get hold of some mature filter media as this will enable you to establish a colony of useful bacteria in your filter much quicker.

This will help your aquarium to cycle quicker too, which will help you to avoid other issues.



Aerated water is essential in the aquarium. Despite living under-water, fish need oxygen. The best way to introduce oxygen to the aquarium is to create surface agitation. There are several ways to do this.

Air pumps will create some surface agitation and certainly have their uses in the aquarium.

Alternatively, you can angle your filter outlet towards the surface of the water.

Or, you could use a wavemaker to agitate the surface and increase circulation.



Circulation is important for a clean, healthy aquarium.

Without enough circulation, you may find that you have areas where dirt and debris can accumulate. This can become a breeding ground for the kind of bacteria you do not want in your aquarium.

So if your filter isn’t strong enough to fully circulate water around your aquarium, or you get dead spots, a wavemaker or powerhead is a great idea.




This is fairly common in the aquarium, particularly in new setups. So it’s worth looking out for.

It is often confused with White spot/Ich and whilst some reports suggest that White spot medication can be effective many also report that it isn’t.

So, if you have been treating for White spot, but it isn’t getting better and fish are dying left right and centre, then it may be time to consider that it may be Epistylis.





Aquarium science

PFK A-Z of fish health

Use and Application of Salt in Aquaculture – IOWA State University

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I am a fish keeping enthusiast with over 20 years experience. I currently keep American Cichlids (CA) which are my favourite fish to keep so far. I started Seriously Fishy as I noticed a large volume of people on various web pages looking for help with Aquarium basics. I created the first Seriously Fishy book to solve the issue in 28 pages, that led to the Seriously Fishy UK fish forum and blog.

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