Corydoras with weird tail rot issue/fungus?

[Maya Boone]

My planted 75 gallon has been set up for 8-9 months and one of the false Julii Corys I got very early on has developed this weird tail rot or fungus problem. I had a couple rummynose with a similar issue (at different times) and I’ve treated with aquarium salt plus Kanaplex. Did Neoplex in the first outbreak as well. The rummynose have gotten better but the Cory doesn’t seem to have had any improvement—in fact over several weeks/months his tail deteriorated more. I originally wanted to wait and see because I know fins can take some time to grow back, but this has me stumped. There is nothing concerning with water parameters (temp of 74-75, pH of 7.2, 0 ammonia, 0 nitrite, nitrate at 20-40 ppm for plants, hardness at 120). I do weekly water changes of about 10-20%. The fish is also swimming around consistently and presumably getting food, as he doesn’t look thin.

Any thoughts? Also attached a photo of the tank!

 

[Fishfur]

I don’t see any overt signs of fungus or inflammation in these pics but the fact that an entire section of tail fin is not only missing but that the caudal stump itself is raw means this part of the fin can never grow back.

What remains of the tail fin looks pretty good but it does appear to be a lighter colour than it should be. Does it look lighter to you too?

When a fin infection penetrates into the body itself, it often becomes a serious systemic infection that is extremely difficult to treat.

But if that doesn’t happen, one can hope the stump will heal over. I’d be wanting to paint the entire fin & stump with Methylene blue just to see if there’s any sign of infection beyond what’s currently obvious & it should help with healing.

You might even try catching this guy in a net and dabbing the stump dry. Then apply some triple antibiotic ointment to it. So long as the skin it’s applied to is dry it will stay on there for quite some time. Protects & aids healing.

But drying off the tail end is not going to be easy with such a small fish & it would be very stressful for the poor guy. And you’d probably get his spines stuck in your fingers - which is very unpleasant for you & no fun for the fish.

It is hard to say whether the original infection is still present but if that raw area can be persuaded to heal over, then the fish should be ok.

 

[Maya Boone]

Thanks for the detailed info! After doing some other research I already have some methylene blue on the way (arriving in two days), but I didn’t initially try this because Kanaplex seemed like a solid treatment that worked for my other fish. This little guy’s situation just didn’t seem to improve. I hope the methylene blue will help! Otherwise would you say the kindest option is to euthanize him? I don’t want him to suffer (or for the disease to spread, although my 10 other Corys seem to be perfectly healthy).

I was just able to snap a clearer picture of him, there’s a little bit of white growth on the tip of his tail that I thought might be fungus.

 

[Fishfur]

I don’t see it but the image isn’t sharply focused.

If the raw area will heal the fish would be fine - he’d be able to live a perfectly good life with only half the caudal fin.

But if it won’t heal or gets larger, then it may not be possible to keep him going.

 

[Fishadict512]

Thanks for the detailed info! After doing some other research I already have some methylene blue on the way (arriving in two days), but I didn’t initially try this because Kanaplex seemed like a solid treatment that worked for my other fish. This little guy’s situation just didn’t seem to improve. I hope the methylene blue will help! Otherwise would you say the kindest option is to euthanize him? I don’t want him to suffer (or for the disease to spread, although my 10 other Corys seem to be perfectly healthy).

I was just able to snap a clearer picture of him, there’s a little bit of white growth on the tip of his tail that I thought might be fungus.

If you have a QT put him in there. You can buy a cheap 5-10 gal tank. In my experience methylene blue stains.

 

[Fishfur]

If you have a QT put him in there. You can buy a cheap 5-10 gal tank. In my experience methylene blue stains.

MB definitely does stain virtually everything & that includes silicone & decor inside tanks. So does malachite green.

 

[Maya Boone]

I did some more research about methylene blue and did a 10-second dip with it today. He did well with it and thankfully I was able to net him really easily without stressing him out a lot. I’ll continue to monitor him and hope things improve! I don’t see any visible stains on him afterward but he did swim back to hide in the plants pretty quickly.

I don’t currently have a QT tank set up but I do have another tank that I can use if needed

 

[Fishfur]

I did some more research about methylene blue and did a 10-second dip with it today. He did well with it and thankfully I was able to net him really easily without stressing him out a lot. I’ll continue to monitor him and hope things improve! I don’t see any visible stains on him afterward but he did swim back to hide in the plants pretty quickly.

I don’t currently have a QT tank set up but I do have another tank that I can use if needed

Did you dilute the MB with water? If so, it isn’t going to stain fish. Has to be applied undiluted directly to the affected area to stain anything not protected by slime coat.

 

[Maya Boone]

Did you dilute the MB with water? If so, it isn’t going to stain fish. Has to be applied undiluted directly to the affected area to stain anything not protected by slime coat.

Ah, I did dilute it—1/2 tsp in a quart of water. Is that an acceptable dose? I read to do 2tsp per gallon so I just did the equivalent amount for my size bowl

 

[Fishfur]

Ah, I did dilute it—1/2 tsp in a quart of water. Is that an acceptable dose? I read to do 2tsp per gallon so I just did the equivalent amount for my size bowl

Used conventionally it’s still an excellent med but to take advantage of the limited diagnostic property that the staining can provide, it must be applied to the fish as it comes from the bottle.

One catches the fish & uses a syringe or dropper to liberally apply the MB to the fish while it’s in the net & temporarily out of water.

No bottle of MB will have instructions for use in this manner. I learned the technique from a vet a very long time ago and it’s never harmed any fish to be treated this way to the best of my knowledge. But the manufacturers prefer to be very conservative so as not to get sued, so this method isn’t mentioned on the product.

You can’t overdose it using it this way yo the very best of my understanding. The minimal amount that rinsed off the fish afterward isn’t enough to be a worry or therapeutic.

 

[Fishadict512]

V

Used conventionally it’s still an excellent med but to take advantage of the limited diagnostic property that the staining can provide, it must be applied to the fish as it comes from the bottle.

One catches the fish & uses a syringe or dropper to liberally apply the MB to the fish while it’s in the net & temporarily out of water.

No bottle of MB will have instructions for use in this manner. I learned the technique from a vet a very long time ago and it’s never harmed any fish to be treated this way to the best of my knowledge. But the manufacturers prefer to be very conservative so as not to get sued, so this method isn’t mentioned on the product.

You can’t overdose it using it this way yo the very best of my understanding. The minimal amount that rinsed off the fish afterward isn’t enough to be a worry or therapeutic.

I will keep this in mind next time I use this! Thanks for the great tip!

 

[Maya Boone]

Used conventionally it’s still an excellent med but to take advantage of the limited diagnostic property that the staining can provide, it must be applied to the fish as it comes from the bottle.

One catches the fish & uses a syringe or dropper to liberally apply the MB to the fish while it’s in the net & temporarily out of water.

No bottle of MB will have instructions for use in this manner. I learned the technique from a vet a very long time ago and it’s never harmed any fish to be treated this way to the best of my knowledge. But the manufacturers prefer to be very conservative so as not to get sued, so this method isn’t mentioned on the product.

You can’t overdose it using it this way yo the very best of my understanding. The minimal amount that rinsed off the fish afterward isn’t enough to be a worry or therapeutic.

Thanks for the advice. I did this today, he doesn’t seem to be any worse but also not any better. I really hope this helps!

 

[Fishfur]

Thanks for the advice. I did this today, he doesn’t seem to be any worse but also not any better. I really hope this helps!

Me too, but there are never any guarantees.

 

[Fishadict512]

Thanks for the advice. I did this today, he doesn’t seem to be any worse but also not any better. I really hope this helps!

Is your fish still eating/ active?

 

[Fishfur]

Thanks for the advice. I did this today, he doesn’t seem to be any worse but also not any better. I really hope this helps!

Did any part of the affected area turn blue after the MB was applied?

 

[mulletmcnasty]

"One catches the fish & uses a syringe or dropper to liberally apply the MB to the fish while it’s in the net & temporarily out of water."

Another lesson learned!

 

[Maya Boone]

Did any part of the affected area turn blue after the MB was applied?

Not that I could see, no. To answer @fishadict512’s question, he had been fairly active up until recently, which is why I was initially waiting to see if his tail grew back (also because my sick rummynose recovered). When I didn’t see any improvement I grew more concerned. Unfortunately it looks like things have gotten worse today and now most of the top of his tail fin is also gone (this has developed literally in the last 24-36 hours, as he lost the bottom half of his tail a while ago—that’s about when I started treatment and didn’t see improvement but decided to wait to see if he recovered along with my other fish that were doing better). He’s also lying mostly in one spot, which isn’t unusual for corys since they’re more nocturnal, but he’s not with the group and seems more lethargic.

I’ve got some clove oil and it seems like with the rapid loss of his top caudal fin I might need to euthanize him. I don’t want him to suffer. I’ve never used clove oil yet but my understanding is that you put a few drops in a small container with the fish, wait for them to go to sleep, and then increase the dosage so they go off slowly. Is that correct?

 

[Fishadict512]

Not that I could see, no. To answer @fishadict512’s question, he had been fairly active up until recently, which is why I was initially waiting to see if his tail grew back (also because my sick rummynose recovered). When I didn’t see any improvement I grew more concerned. Unfortunately it looks like things have gotten worse today and now most of the top of his tail fin is also gone (this has developed literally in the last 24-36 hours, as he lost the bottom half of his tail a while ago—that’s about when I started treatment and didn’t see improvement but decided to wait to see if he recovered along with my other fish that were doing better). He’s also lying mostly in one spot, which isn’t unusual for corys since they’re more nocturnal, but he’s not with the group and seems more lethargic.

I’ve got some clove oil and it seems like with the rapid loss of his top caudal fin I might need to euthanize him. I don’t want him to suffer. I’ve never used clove oil yet but my understanding is that you put a few drops in a small container with the fish, wait for them to go to sleep, and then increase the dosage so they go off slowly. Is that correct?

Is he in a separate QT tank? Do you have sharp objects in the tank? I've never heard of this before. It might be time to let your fish go...

 

[Maya Boone]

Is he in a separate QT tank? Do you have sharp objects in the tank? I've never heard of this before. It might be time to let your fish go...

He’s not in a separate tank. There’s no sharp objects, just the same rocks I’ve always had and used in other tanks, and some driftwood.

 

[Fishadict512]

I'm not really sure what's going on...

 

[Fishfur]

Not that I could see, no. To answer @fishadict512’s question, he had been fairly active up until recently, which is why I was initially waiting to see if his tail grew back (also because my sick rummynose recovered). When I didn’t see any improvement I grew more concerned. Unfortunately it looks like things have gotten worse today and now most of the top of his tail fin is also gone (this has developed literally in the last 24-36 hours, as he lost the bottom half of his tail a while ago—that’s about when I started treatment and didn’t see improvement but decided to wait to see if he recovered along with my other fish that were doing better). He’s also lying mostly in one spot, which isn’t unusual for corys since they’re more nocturnal, but he’s not with the group and seems more lethargic.

I’ve got some clove oil and it seems like with the rapid loss of his top caudal fin I might need to euthanize him. I don’t want him to suffer. I’ve never used clove oil yet but my understanding is that you put a few drops in a small container with the fish, wait for them to go to sleep, and then increase the dosage so they go off slowly. Is that correct?

It sounds like the poor fish has an extremely severe fin infection which has probably become systemic at this point given how that caudal stump looked in the pics.

I think sending him over the bridge is likely the best thing given the shape he’s in.

A dose of about 400mg (1/8 tsp) per litre (quart) of water is fatal. Fish lose consciousness & then stop breathing. They feel nothing after they fall asleep.

Clove oil isn’t very soluble so it helps if you use a half a cup of very hot water to mix the oil with first & then add cooler water.

Even for very small fish I prefer to use a container that holds at least a gallon of water with space to spare & obviously it has to be a lot larger for much larger fish.

I mix enough oil to dose 2-3 litres of water with 1/2 cup of hot water first, then a cup of cool to cold water

Then I top it up to make 1 litre & shake it hard. It should look cloudy. I use a bottle to mix it as a bottle is easy to shake.

I put one or two litres of water in the container & add about 1/4 of the oil & water mix & swirl it around.

I add the fish & slowly add more of the oil/water mix until the fish rolls over & then sinks & breathing slows down.

I’ll add the remaining mix when the fish is lying on the bottom & leave it there for an hour.

If you want a little extra insurance that it will never ever wake up, you can add a cupful of alcohol - usually vodka is advised but there’s no reason not to use something less costly like rubbing alcohol, which is more potent anyway.

 

[Maya Boone]

Thanks for the detailed info again. I’ll go ahead and put him down this evening.

 

[Fishfur]

Thanks for the detailed info again. I’ll go ahead and put him down this evening.

Very sorry it’s come to this. My condolences.

 

[Maya Boone]

Very sorry it’s come to this. My condolences.

It’s okay, part of the hobby. Just glad I have the stuff to let him go off peacefully rather than fighting the sickness for who knows how long!

 

[Fishfur]

It’s okay, part of the hobby. Just glad I have the stuff to let him go off peacefully rather than fighting the sickness for who knows how long!

Indeed. Prolonged bouts of sickness are no fun for us or the fish & I do think it’s kinder to save them that.

 

[Fishadict512]

Very sorry it’s come to this. My condolences.

Mine too. poor fish

 

[mulletmcnasty]

Sorry this has happened. I feel really guilty when I put down a fish, but I guess it's for the best.

 

[Fishfur]

Sorry this has happened. I feel really guilty when I put down a fish, but I guess it's for the best.

Me too, even when I’m very sure it’s the only kindness that I can give them.