Epistylis in tank plus Betta melting fins???

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.


Aquarium Advice Newbie
Oct 4, 2023
Strap in, this is going to be a bit of a long one. Last week i introduced this cute lil baby super red pleco to my planted 20 gallon betta tank. A week later (2 days ago) I notice that the new pleco is riddled with white spots all over his body, and some had started to spread onto my Betta's fins. After extensive research, what I initially thought was ich that was in my tank, was actually epistylis! responders on reddit have noticed it. They said to use Ich-X, but that's not readily available in Montreal. I researched what the ingredient is that's necessary to rid this epistylis, and I learn that it's Malachite Green. I went the next day and purchased a bottle of Malachite Green by Kordon. I added Fluval Aquarium Salt to the tank, 2TBSP of it, and the recommended dosage of the Malachite Green. Today as I was doing the 25% water change and retreating the water, I noticed that some of the fins of my crowntail betta are turning white and cloudy at the tips and looks like they're melting????

I did a water change not long before seeing this incident, and my ammonia, nitrite, and nitrate levels were all in the clear (i wouldn't say complete 0 for nitrates as that's unrealistic but well below 20). I had bought some new plants recently and the dreadul transition phase of the plants melting their leaves off and stuff may have caused a spike in the bio load. But it is odd that I hadn't seen any fin melting up until today when starting treatment. Could it really by fin rot and my ammonia levels had truly spiked and I didn't notice it? Or am I dosing something wrong with the meds?

Also, if ther's any tips or advice anyone would like to share in regards to treating epistylis (or ich, still not 100% that it's epistylis or ich, the medicine says it cures both so there's that)


  • berry1.jpg
    247.5 KB · Views: 47
  • berry2.jpg
    253.9 KB · Views: 12
  • bery2.jpg
    237.4 KB · Views: 14
  • apple 1.jpg
    apple 1.jpg
    189.9 KB · Views: 24
  • apple2.jpg
    138.8 KB · Views: 42
Unfortunately ich and epistylis have different treatment methods, particularly with regards water temperature.

With ich you need to speed up the lifecycle of the parasite by raising the water temperature, whereas epistylis thrives in warmer water, so you need to lower the water temperature to slow its growth.

I dont know as much about epistylis as ich, but ill tell you what i know about ich.

Ich parasites goes through a life cycle. You will first notice it during the infected stage, where it presents as equally sized, white dots like grains of salt on the fish. During this stage the parasites are feeding. After this stage the parasites will leave the fish and drop into the substrate to breed, and it will appear like your fish is cured. But the parasites are still in tank and will reinfect the fish some time in the future. Once the parasites have bred, the new parasites will go into the water looking for fish hosts. This is called the freeswimming stage and its only during this stage that the parasite can be killed. Once the parasite finds a host, we return to the infectious stage and the lifecycle continues.

Raising the temperature is important because it speeds up the lifecycle and reduces the time between the infectious stage and the freeswimming stage where your treatment can be effective. In a cold water aquarium the lifecycle is about 3 months. In a typical tropical aquarium the lifecycle is about 1 month. Raising the temperature to 27c/ 81f reduces the lifecycle to about 1 week. Further raising the temperature to 30c/ 85f can kill the parasites with no need for medication.

So what we can take from above is that you medicate the tank during the infected stage, but the medication will have no effect on the infected fish. It will either die or survive regardless of anything you do. When the infection clears up that just the parasites naturally moving onto its next lifecycle stage. The medication still needs to be in the water during the freeswimming stage to kill the parasites, which if you dont elevate the temperature can be 3 or 4 weeks later. So raise the temperature, medicate the tank, frequent water changes and gravel vacuuming to reduce the number of parasites that your medication needs to treat, ensure you redose medication to account for water changes, make sure the medication stays in the water for 4 or 5 days after the last signs of infection have disappeared.
Thank you so much for your insight. Knowing that it's epistylis, I lowered the temp of the tank from 80F to 77F, and immediately the next day is when I noticed my betta's fins melting. When I turned it back up after a day and a half, I checked on them this morning and the melting had stopped (but some of his beautiful fins are chopped :( ) The treatment is definitley working, there are visibly way less spots on the red pleco, and the tiniest dots remain on my betta however he is exhibiting clamped fins behavior (hoping he's just unsettled from all the water changes and disturbances (also decided to net him and give him a 10 second methlyne blue bath for the fin rot).

But yes your response validated my concern, which is how long shall i keep medicating and doing water changes so the disease does not return? Would medicating the tank for 3-4 weeks not cause a cycle crash? or be too much for the fish and plants? I'm really worried that after all that salt and medication, the nitrfiying bacteria would have died off and I end up with an even bigger problem on my hands (my other tank is going through reseal repairs and I dont have another tank.... may have to run to canadian tire and buy myself a storage bin as an emergency tank.)

I'm hoping epistylis is much less resiliant to get rid of than ich as you just described. Shall I continue adding salt? I stopped adding salt in fear that my betta's melting fins were also because of the salt (since it aggravates their slime coat, maybe my betta is currently too vulnerbale to be going through salt and malachite green treatment simultaneously.)
I'm new to this forum and forgot to respond directly to you before responding, updates and questions are on post #4 of this thread. Thank you again for your insight it's greatly appreciated :)

Latest posts

Top Bottom