Will cories tolerate methylene blue?

Fishstery

Hi everyone!

I just set up a new tank this week using preseeded media and wanted to try out some pygmy cories with my betta. After a lot of time and hard work I managed to treat my bettas dropsy and don't want to risk him getting sick again so I decided I'm going to QT the pygmy cories for 2-3 weeks. I got 6 and holy cow they are TINY. I've never kept them before but I'm excited. Now that I got them set up in their QT tank (heater and small sponge filter that isn't cycled so I will have to do daily WCs) I noticed they all have mild tail rot, or their tails were nipped by something else at the store. I wanted to treat them with methylene blue regardless since it's gentle and a great anti parasitic, fungal, AND bacterial "disenfectant" but im apprehensive about using it on juvenile scaleless fish. Have any of you used it on your corydoras? Thanks!
 

Demeter

I've used M. blue on my pygmy corries with no problems, so far I have yet to have adverse reactions from any species of fish with M. blue.
 
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Fishstery

I've used M. blue on my pygmy corries with no problems, so far I have yet to have adverse reactions from any species of fish with M. blue.
Thank you for your experience! Did you do the full dose (im using kordon) or did you do a half-dose?
 
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Demeter

I put the corydora in a small cup of water with a few drops. Very rarely do I follow the directions for M. blue as it is very safe and overdosing with it is near impossible.
 
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Oriongal

I also have used MB (and salt) with corys with no adverse effects. As Demeter said I'm not sure it is possible to overdose it.
 
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Fishstery

I also have used MB (and salt) with corys with no adverse effects. As Demeter said I'm not sure it is possible to overdose it.
Did you only use it as a bath too or did you treat the actual hospital/QT tank with it? I was looking to just add a dose to the QT tank for a week or so while their tails heal up
 
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Oriongal

Did you only use it as a bath too or did you treat the actual hospital/QT tank with it? I was looking to just add a dose to the QT tank for a week or so while their tails heal up
Generally I've only used it as a bath, mostly because I tend to have plants even in quarantine. And it may kill the cycle, so if you're using cycled media or your QT is cycled, you probably would need to take that into consideration same as you would when using antibiotics.

But there are some times I have set up a bare QT to use it continuously.

For continuous use, I've most often used it as palliative care for fish that were having trouble breathing, such as fish arriving with ammonia-burned gills in shipment. Naturally fish in that bad a shape aren't going to have an optimistic outlook to begin with, but sometimes even one survivor in that situation is a success.
 
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Fishstery

Generally I've only used it as a bath, mostly because I tend to have plants even in quarantine. And it may kill the cycle, so if you're using cycled media or your QT is cycled, you probably would need to take that into consideration same as you would when using antibiotics.

But there are some times I have set up a bare QT to use it continuously.

For continuous use, I've most often used it as palliative care for fish that were having trouble breathing, such as fish arriving with ammonia-burned gills in shipment. Naturally fish in that bad a shape aren't going to have an optimistic outlook to begin with, but sometimes even one survivor in that situation is a success.
I'm aware of its effects on plants and BB, this is just a plain old bare bottom 5 gal QT/hospital tank with an uncycled sponge filter and rock hide that I only fill with 2 gallons of water to make the every other day WCs easier. I just dosed the entire tank with the methylene blue, but did a quarter dose just to err on the side of caution especially since 5 out of 6 of the cories are definitely juvies. Not sure if it was just a coincidence but they got super active after I gave them their first WC and added the m. blue. It does say on the bottle it helps with stress and also oxygen absorption so maybe that had something to do with it. I plan on keeping them in the m. blue for about 3-5 days to allow their tails to start to heal up without the risk of fungus developing and then I will transition them back to unmedicated water. Other than their tails I don't see any signs of parasites but I understand the life cycle of some parasites are over a week so hopefully nothing else pops up and I can get them moved over to the pond tank sooner rather than later.
 
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Michael Hammond

I hatch all my Corydoras eggs in Methylene Blue.
 
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Fishstery

Just an update: I've lost 2 out of 6 pygmy cories after adding the methylene blue. The 3rd one is floating upside down but still alive. It could just be a coincidence, I added a half dose of m.blue 24 hours after putting the cories in QT, and the 3 that had issues were the 3 smallest ones (they were SO tiny, looked very young to me). I removed the m.blue during tonight's water change, I think I will just stick to plain old water changes and only redose the m.blue if their tails start to get fungus or recede more. It may or may not have had something to do with the m.blue but again I only had them since Friday, they were very young, and also newly stocked at the fish store when I picked them up so they definitely have traveled quite a bit in the last week. Unfortunately pygmy cories are a rare find in my area and what's a 3 dollar fish in store is a 8-12 dollar fish online plus shipping, so whatever lives through QT is what will go into my tank (I know a shoal of 3 isn't preferable but I don't see me tracking down any more in the near future without sourcing them online) I already had to drive over an hour to get to the only store that had them, so hopefully the remaining 3 will survive QT.
 
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Oriongal

I am sorry that you lost some of them, but still can't imagine the MB would be a reason. Especially at half dose.

It's been used for decades; when I got my first tank in the 1970's, pretty much all we had for medications were salt, methylene blue, malachite green, and potassium permanganate. Of those MB is the mildest. It's sometimes used in human medicine as well.

Formalin is a medication that can kill corys at strengths that other fish tolerate well, and it can be an ingredient in blue liquid medications (usually for parasites). You'd smell it though, it has a stronger smell than plain MB.
 
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Fishstery

I am sorry that you lost some of them, but still can't imagine the MB would be a reason. Especially at half dose.

It's been used for decades; when I got my first tank in the 1970's, pretty much all we had for medications were salt, methylene blue, malachite green, and potassium permanganate. Of those MB is the mildest. It's sometimes used in human medicine as well.

Formalin is a medication that can kill corys at strengths that other fish tolerate well, and it can be an ingredient in blue liquid medications (usually for parasites). You'd smell it though, it has a stronger smell than plain MB.
Like I said, it was probably just a coincidence. The ones I lost were obviously very young and hadn't been at the store more than 2 days before I bought them, so they did a lot of transporting the week I took them home. I'm sure being transported twice and also being put into 2 new tanks within days of each other stressed them out a good bit as well. The other 3 are still doing well, it will be one week this Friday since they were placed in QT. Considering moving them over to the main tank after that point, but I haven't decided yet. It's getting tiresome doing every other day WCs and I can imagine the QT tank is stressful for them having to get scared by the constant WCs, also the absence of sand and live plants probably isn't good either. I can imagine there is trace ammonia buildup on the days I don't do WCs but I dose the tank with prime on those days just to be cautious.
 
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SallImSayin

I've used them on new corydoras as a preventative measure. No problem. I only do a dip with the newbies, though. I treat for a 3g dip, which lasts 10 seconds. I treated the whole goldfish tank, twice, over several days, when something got into the tank (kids), and they made a full recovery.
 
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