How to treat Epistylis in fish

If you’re an aquarium enthusiast like me, you know that keeping your fish healthy is one of the most rewarding parts of the hobby. But every once in a while, we come across challenges, and Epistylis is one of those tricky ones. Don’t worry; I’ve got your back with everything you need to know about this pesky parasite, from understanding what it is to how to get rid of it safely.

So, What Exactly is Epistylis?

Epistylis might sound complicated, but it’s simply a type of freshwater protozoan that can cause some pretty uncomfortable issues for fish. It forms colonies of tiny stalked ciliates (imagine little microscopic creatures waving tiny hairs), and these protozoans like to attach themselves to the skin, fins, and gills of fish. It is technically not a true parasite but an epibiont that utilises fish only as a substrate for attachment. These epibionts don’t directly hurt the fish but create open wounds that will most likely lead to dangerous bacterial infections.

Image obtained from ©Rogelio Moreno G.

You might notice white or greyish, cottony patches on your fish, and that’s a big red flag. Don’t mistake it for a fungal infection, though—Epistylis has its own special set of challenges.

The Life Cycle of Epistylis

Now, I know life cycles aren’t the most thrilling topic, but understanding how Epistylis lives and spreads will really help. These parasites love dirty water with lots of organic waste (yep, they’re kind of gross that way). They settle on surfaces and reproduce like crazy, especially if the water quality isn’t up to par. Unlike some parasites that jump from fish to fish, Epistylis prefers spreading through water, making pristine water conditions your best weapon against them. 

Follow the numbers from 1 to 8 in the figure above to see how Epistylis spreads to fish. Obtained from The Southeastern Association of Fish and Wildlife Agencies (SEAFWA)

Is Epistylis Contagious?

Yes, but only to other fish. The good news is, Epistylis won’t affect us humans. You can safely handle your fish, but I still recommend wearing gloves to avoid any accidental infections from bacteria that might be lurking around. Prevention is easier if you act quickly, so improving your tank’s water quality is key.

Signs to watch for

Keeping a close eye on your fish is crucial, especially when trying to spot the early warning signs of Epistylis. One of the most noticeable symptoms is the appearance of white or gray cotton-like growths. These fluffy patches often develop on the skin, fins, or even the gills, creating a concerning sight that should never be ignored. These growths aren’t just a visual issue; they signal that your fish are experiencing severe discomfort and may be vulnerable to secondary bacterial or fungal infections.

Images sourced from FishHelpIo

Another sign to watch for is lethargy and a noticeable lack of appetite. Fish that are typically active may become sluggish and uninterested in food, a strong indicator that something is amiss. 

Another clue to look out for is clamped fins. Healthy fish usually have fins that fan out gracefully. However, when they are stressed or unwell, their fins may clamp down close to their body. This posture is a clear sign of discomfort, and in the context of Epistylis, it suggests your fish are feeling the strain of the infection.

An example of a goldfish with clamped fins

Lastly, labored breathing can occur, particularly if the gills are affected. You may notice your fish struggling to breathe, gasping at the water’s surface, or exhibiting rapid gill movements. Difficulty breathing is always a red flag, as it indicates that your fish are not getting enough oxygen, which can quickly become life-threatening.

Being attentive to these signs and taking swift action can make all the difference in treating and saving your fish from Epistylis.

Treating Epistylis: Step by Step

Alright, let’s talk about how to help your fish get better. Here’s what you can do:

1. First, Clean Things Up!
   • Perform a 20-30% water change and vacuum the substrate to get rid of any waste that’s built up.
   • Check your water parameters with a reliable test kit. Make sure ammonia and nitrites are zero, and keep nitrates as low as possible, preferably below 20 ppm. 
   • If your nitrates are still higher than 20ppm, perform another 20-30% water change and continue to vacuum the substrate.

2. Boost Oxygen Levels
   • Adding an air stone or increasing the flow from your filter can do wonders for oxygenating the water and keeping your fish happy.

3. Try a Salt Bath
   • If the case isn’t too severe, give your fish a salt bath using aquarium salt (never table salt!). Dissolve 1 tablespoon per 18 litres of water and gently place your fish in the bath for up to 10 minutes. Ensure the water it is bathing in is well-aerated. Different species have varying tolerances for salt baths. Watch diligently and if the fish is in distress, quickly return them to fresh dechlorinated water.

4. Treat with a broad spectrum antibiotic
   • Epistylis is typically a sign of a serious bacterial infection. Fish with epistylis commonly die very rapidly, not from the epistylis, but rather from an internal bacterial infection.
     It is recommended to treat with a broad spectrum antibiotic. This works best when it is mixed in with the fishes’ food and medicated for 10 days.
   • Give us a call or email us if you need help with choosing the right antibiotic.
     

Prevention is Better Than Cure!

Want to keep Epistylis away for good? Well, I can’t promise that it will be kept away for good, but here are some tips to minimise the chances of epistylis from reoccurring. Here’s how:

• Regular water changes are your best friend. Once a week is ideal
• Check your water parameters frequently to avoid ammonia or nitrite spikes.
• Feed appropriately. Uneaten food decays and ruins water quality. If you see uneaten food, after an hour, best to scoop them up with a net and discard.
• Quarantine new fish before adding them to your main tank to prevent introducing new parasites.

Final Thoughts

Treating Epistylis may seem overwhelming at first, but don’t worry—you’re not alone in this. By taking quick action and making some changes to your aquarium maintenance routine, your fish should be back to their vibrant selves in no time. Keep up the great work, and remember: a clean tank is a happy tank!

Stay passionate about your fishkeeping journey, and feel free to reach out if you need more advice. We’re all in this together, learning and growing as we care for our beautiful aquatic worlds.