Red velvet Cory - erratic swimming and weird markings


Stable tank, been establishes and cycled for some time now.

This little guy started listing to one side during swimming and started swimming erratically.

I immediately moved it to a quarantine tank to observe - also cycled and running.

That was about 10 days ago. He looked bloated so I started feeding him skinned, boiled peas every other day assuming he was constipated.

I didn’t see any improvements after a week, so I started medicating with Paracleanse and Maracyn assuming it might be a parasite, and that weakened immunity might have led to a bacterial infection as well.

His swimming seems less erratic now but he is still not fully normal. However, today I noticed these strange marks on one side of its body - the same side he was listing towards while swimming.

Here’s a video


That looks like a girl, based on fin shape, and female cories tend to be rounder since they carry eggs.
As for the spots, it definitely looks like some sort of fungus (or maybe a bruise, which my cories get on their pectoral fins if they try to snuffle under something heavy for too long, like a piece of driftwood).

Be careful about what meds you're using, as cories are scaleless and can be negatively affected by many medicines. What I'm worried about is that what she has now is columnaris. In which you'd need to check which meds are safe to use with cories to treat that. I like Fritz meds, as they seem safe for most fish. They've always worked for me, though there are mixed reviews on them (like all meds, honestly. I think the effectiveness has a lot to do with water chemistry).

Sorry that I couldn't be of more help, but I hope I helped to steer you in a better direction.


So, I watched the video. the tank is dirty, I mean seriously dirty, I see the poop floating around fungus and bacteria kicking up when he moves and he's laying in it constantly because he's a bottom dweller he's also eating it so I won't rule out an internal bacteria infection that's causing swim bladder issues.

This is your problem in a nutshell, the water quality and tank condition is bad, you need to water change and vacuum the substrate, and do it daily until it's spotless and clean again, and the whiteness should recede and those bubbles should go away and she should heal up and get back to normal.
even the snail that cruises through has junk on it that's not supposed to be there from the buildup in the tank.

I don't think you need meds, you need a much cleaner environment for the fish. meds aren't going to fix anything if you don't fix that first.


That’s the quarantine rank - not the main tank and he is the only fish in it. The water is being changed daily. What you are seeing as dirt is most likely remnants of the boiled peas because the cloudiness didn’t start until after I started feeding it peas.
And additionally - because the cory is being medicated, I am not using anything except mechanical filtration - which exacerbates the cloudiness


Forgot to provide an update: she slowly improved with medication and boiled peas and is back in the main tank now (as of 8/20).

As a result of this experience I am now feeding all the cories a boiled peas twice a week instead of their normal sinking pellets.

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