Molly with white spots. Is it fungus?

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Fish Fanatic
Sep 11, 2022
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Newmarket, Canada
Hello all.

I noticed last night that one of my full black mollies has some "faint" or "soft" white spots on him. At a glance, it does not look like ich like I experienced before, these seem a tiny bigger, and it's kind of fainted (the picture below doesn't make it justice). From what I saw online, this could be fungus.

I did have a camallanus issue which I've been treating with Fritz Expel-P once a week for three weeks now (going to the fourth week tomorrow). I'm not sure if that could cause it.

How can I best treat this? I'm in Canada, so I don't have easy access to many meds. I do have Melafix and API General Cure, if helpful. From my research, salt sounds like a good medicine for this issue as well. Also, should I treat the whole tank or just the one molly separately? There are other mollies in the tank as well, but they don't show any signs of the same issue.

Thank you.


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It's excess mucous caused by something in the water irritating the fish. It could be from ammonia, nitrite, nitrate, low pH or the medication used to deworm them.

Treatment involves doing a big (75%) water change and gravel cleaning the substrate every day for a week.

If you are deworming the fish tomorrow, do a 75% water change and gravel clean today and tomorrow before treatment, then wait 2 days before doing another water change. Then do them each day for a week after that.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.


What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).


To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.

There are 3.785 litres in a US Gallon
There are 4.5 litres in a UK gallon

When you measure the height, measure from the top of the substrate to the top of the water level.

If you have big rocks or driftwood in the tank, remove these before measuring the height of the water level so you get a more accurate water volume.

You can use a permanent marker to draw a line on the tank at the water level and put down how many litres are in the tank at that level.

There is a calculator/ converter in the " Calculator" under "Useful Links" at the bottom of this page that will let you convert litres to gallons if you need it.

Remove carbon from the filter before treating with chemicals or it will adsorb the medication and stop it working. You do not need to remove the carbon if you use salt.

Mollies do best in water with a GH above 250ppm and a pH above 7.0.
I found out yesterday that nitrites were high. I’m not sure how the cycle got screwed up. I did do a 50% water change yesterday, will do one today again if 75% and add expel-p. Will follow your advice and hopefully get the fish healthy again.

Thank you 🙏

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