Corydoras Won't Stop Scratching

I've made multiple posts on this subject. My corydoras will not stop scratching against the substrate and rocks in my tank. I performed one Methylene Blue bath for each fish, a week's worth of Prazipro, and another week's worth of orally fed Metro+. I hadn't observed them much after that, but today I saw one of them scratching against a rock.

At this point, I'm wondering if it's normal corydora behavior. Here's something I found on a forum, which isn't completely reliable, but has something to do with where I'm going with this: "After researching, I found out this isn't that uncommon for them. As they often get material lodged within their gills that they will try to get out. It can also be a result of high Nitrate levels, so you should check those."

Recently, my mystery snail laid eggs on the cover of my aquarium. There are probably about fifty snails in the tank now, which explains why my nitrate levels are around 40 ppm. However, I'll be giving most of them to my LFS when they get slightly larger and I'll also be giving my rhino pleco to them as well. He's too aggressive towards all my bottom feeders and he'll outgrow the 55-gallon. I think his removal will greatly benefit their environment as well as the nitrate levels. Maybe the nitrate levels are too high? Maybe they have debris lodged in their gills? I don't know. I'm getting really frustrated, but I'm mostly concerned for their health. Thank you to whoever responds.

One more thing: I found a couple of what looks like corydora eggs on the side of the aquarium. Is this a sign that they're healthy? I don't know what to think anymore...

Parameters: 0, 0, 20-40
Temperature: 76 degrees

 

I haven't seen any of your other posts, sorry, and i'm no expert. but if you think the nitrates are high, you can always do a 30% + wc to see if their behaviour changes as the levels go down? sorry, I don't know how often you do those from your post...

 

I haven't seen any of your other posts, sorry, and i'm no expert. but if you think the nitrates are high, you can always do a 30% + wc to see if their behaviour changes as the levels go down? sorry, I don't know how often you do those from your post...

I just performed a 50% water change yesterday. I do this once a week. Thanks for the response.

 

figured as much... sorry not to have anything more useful. all I know is that my cory's don't scratch like that (yet) and i'd love to help you more. I hope someone can!

 

figured as much... sorry not to have anything more useful. all I know is that my cory's don't scratch like that (yet) and i'd love to help you more. I hope someone can!

Thanks! I just saw my rainbow shark scratching as well, so I'm assuming it's the nitrates. After all, they're all sensitive fish. I'll try to remove my mystery snails as soon as possible and perform one more water change tomorrow.

 

Thanks! I just saw my rainbow shark scratching as well, so I'm assuming it's the nitrates. After all, they're all sensitive fish. I'll try to remove my mystery snails as soon as possible and perform one more water change tomorrow.

keep an eye out for ich! I know you just treated but if the parasites weren't killed and went into the next stage of their life and disappeared for a wee while, only to hatch and return, you might hafta re treat. i'm very hesitant to medicate without knowing exactly what's wrong because some meds kill your BB cycle, others can harm some fish... just watch for other distress signs:

white stringy poo
not eating or spitting their food back out
loss of scales (looks like dark dots)
white spots
fluffy patches (often white or grey)
pale colouration

I hope the issue is the nitrates because you can absolutely control that one!

 

keep an eye out for ich! I know you just treated but if the parasites weren't killed and went into the next stage of their life and disappeared for a wee while, only to hatch and return, you might hafta re treat. i'm very hesitant to medicate without knowing exactly what's wrong because some meds kill your BB cycle, others can harm some fish... just watch for other distress signs:

white stringy poo
not eating or spitting their food back out
loss of scales (looks like dark dots)
white spots
fluffy patches (often white or grey)
pale colouration

I hope the issue is the nitrates because you can absolutely control that one!

Thank you!

keep an eye out for ich! I know you just treated but if the parasites weren't killed and went into the next stage of their life and disappeared for a wee while, only to hatch and return, you might hafta re treat. i'm very hesitant to medicate without knowing exactly what's wrong because some meds kill your BB cycle, others can harm some fish... just watch for other distress signs:

white stringy poo
not eating or spitting their food back out
loss of scales (looks like dark dots)
white spots
fluffy patches (often white or grey)
pale colouration

I hope the issue is the nitrates because you can absolutely control that one!

Hello. I performed a large water change today and made sure to vacuum any feces that was left in the substrate. I also removed the majority of my mystery snails as well as my rhino pleco and gave them to my LFS. The nitrates are under 20 ppm at the moment. I'll probably be doing one more water change tomorrow. Thank you again.

 

Hello. I performed a large water change today and made sure to vacuum any feces that was left in the substrate. I also removed the majority of my mystery snails as well as my rhino pleco and gave them to my LFS. The nitrates are under 20 ppm at the moment. I'll probably be doing one more water change tomorrow. Thank you again.

No worries at all...I hope the itching/scratching stops. I've seen a few other posts that suggest some fish learn to flash against the substrate to get the food leftover to float up and then eat it. smart buggers, aren't they? so the key is seeing if the other signs crop up.

sorry you had to rehome your nails and pleco but if this keeps your other fish happy and itch-free, then yay!

 

No worries at all...I hope the itching/scratching stops. I've seen a few other posts that suggest some fish learn to flash against the substrate to get the food leftover to float up and then eat it. smart buggers, aren't they? so the key is seeing if the other signs crop up.

sorry you had to rehome your nails and pleco but if this keeps your other fish happy and itch-free, then yay!

I hope it stops as well. I had that pleco for over a year. He was only an inch or two when I got him and now he's about eight inches. I'll miss him, but I need to think about every one in the tank. I think this will be good for them. I'll keep updating you on the progress.

 

Hello again. My nitrates are down to 10 ppm. I just checked last night. They're still scratching, especially my albino rainbow shark. This is so frustrating and I have no idea what to do at this point.

 

So you've only done one meth blue bath ever? They usually need to be repeated in order to be effective.

 

Yes. I stopped at one because of how difficult it was to catch the fish. Took me almost an hour to catch all the corydoras. Regardless, I don’t have high hopes about meth blue working in the first place. I’ve tried prazipro and metro+, which treat similar things, and neither of them helped whatsoever.

EDIT: I forgot to mention this. I have multiple species of corydoras. When I bought them, I wasn’t aware that they shouldn’t be kept this way. I’ll be removing the majority of my corydoras, excluding the peppered (x2). Once I return them to my LFS, I’ll be getting around seven brand new peppered corydoras.

EDIT: I’ve already caught my albino, bronze, and panda corydoras. They’re in a 2.5 gallon tank and will be sent to my LFS as soon as possible tomorrow. I put the seven peppered corydoras in the 55-gallon with the other two corydoras.

 

Meth blue can treat things that metro and prazI cannot. It wouldn't be a bad idea to keep them in a QT tank so it's easier for you to catch them to do baths, or you could give them baths in the 2.5 gal so it's a little easier (you could do all at one time). Since they're still scratching and the prazI and metro aren't helping, I'd do more.

 

Meth blue can treat things that metro and prazI cannot. It wouldn't be a bad idea to keep them in a QT tank so it's easier for you to catch them to do baths, or you could give them baths in the 2.5 gal so it's a little easier (you could do all at one time). Since they're still scratching and the prazI and metro aren't helping, I'd do more.

Okay. I'm going to get my water tested first for anything that could possibly be causing the scratching. If everything comes out positive, I'll most likely be relying on the meth blue bath. Thanks for the input. Do you have any idea of what I should be looking for when getting the water tested? Phosphates, nitrates, heavy metals, etc.

 

Prime should take care of heavy metals. Ammonia, nitrites, and nitrates are the only things I would blame; I've never heard of high phosphates (or other things in the water) causing something like this, so I wouldn't know what else to test for.

 

Prime should take care of heavy metals. Ammonia, nitrites, and nitrates are the only things I would blame; I've never heard of high phosphates (or other things in the water) causing something like this, so I wouldn't know what else to test for.

Okay, I’ll do some more research on what to test. I just made a T-chart to help me figure out what was going on. It compares the two problems that I think might be causing the scratching. I’m still convinced that there’s something wrong with my water chemistry. By the way, the new corydoras I added last night started scratching immediately. If this were a parasite, wouldn’t it take time for them to start showing symptoms? Here’s the T-chart. Some of it may be confusing, so feel free to ask questions. Let me know what you think:

 

Can you take a video of them scratching?

 

Can you take a video of them scratching?

Sure, I'll try. I'll be back with it in a little while.

Sure, I'll try. I'll be back with it in a little while.

I'm back. I tried for about 20-30 minutes, but I couldn't record any of it. Here's some similar footage I found of what they look like when they scratch:
Rainbow Shark (her fins don't seem so clamped and she looks a lot more active than this guy)

Corydoras (this is the closest thing I could find; they do this against leaves and rocks; my danios do the same)

 

I might be tempted to try another antihelminthic, something other than metro or prazi. Or you could move the affected fish to a QT and add meth blue directly to the tank, with every other day water changes and dosing (since baths are hard with so many fish).

 

I might be tempted to try another antihelminthic, something other than metro or prazi. Or you could move the affected fish to a QT and add meth blue directly to the tank, with every other day water changes and dosing (since baths are hard with so many fish).

It seems as though all of my fish are affected. I’m getting my water tested today. If it ends up being a parasite, I’ll try putting meth blue directly in the tank.

 

It'll stain the silicone and decor in the tank, so be aware of that.

 

It'll stain the silicone and decor in the tank, so be aware of that.

Thank you. I couldn't get anything other than the basics tested, which all ended up being perfect. I'm going to get it tested at Ecolab to see if they can find anything. Once the results come back, I'll update you. At this point, however, I'll probably try meth blue just in case it works. They're scratching so often that some of the fish have small wounds. There's also one danio that was wedged between two stones when I got back home. When I helped him out, it seemed as if he had white patches on his body and white fuzz on his head. He swam oddly for the rest of the day. When I saw him this morning, he still had the patches, but he was swimming normally and acting fine. It sounds like columnaris, but no other fish has it. I'll probably separate him today and perform a large water change. Can parasites cause secondary issues? It seems as though that's what's happening if I'm wrong about the water quality. I still don't understand why previous medications didn't work. What's the difference between meth blue and the medications I used?

EDIT: I was just doing some research on columnaris.
I've seen people who claim they've experienced scratching when their fish had columnaris. It's also said to last for months without treatment, and can have exterior or interior effects (explains why not everyone has the wounds/ulcers I've been seeing lately). I also remember having about 17 danios in my tank. I'm down to 11 now and have no idea where they went. The article says that columnaris can kill many fish within hours. They all disappeared within a day. If columnaris is the cause, what should I treat the tank with?

EDIT: First photo is of my one of my leopard danios. His stomach has a sharp point, which is probably him eating too much. What I’m worried about is the ulcer near his fin. It’s slightly visible in the photo. You’ll see a pink spot. The second photo is of my leopard spotted danio, which is the fish I think has columnaris. You can see the saddleback in this picture. There’s one more spot on his head.

 

Ich could be the problem. I can relate. A while back some of my fish were scratching and soon found they had white spots on them. I didn’t know what it was at the time, but figured out it was Ich. Keep an eye out and if they do get white spots, use an ich guard to cure it

 

Ich could be the problem. I can relate. A while back some of my fish were scratching and soon found they had white spots on them. I didn’t know what it was at the time, but figured out it was Ich. Keep an eye out and if they do get white spots, use an ich guard to cure it

Thanks, I’ll look out for that. A few fish had what I though was ick, but ended up just being a couple grains of sand. I’m hoping it’s columnaris, as I’ll be able to treat that.

 

I'm happy to help, if you have any other symptoms of a sickness post it and maybe the community and I can help you some more.
If it is columnaris look for this
"An infection will usually first manifest in fish by causing frayed and ragged fins. This is followed by the appearance of ulcerations on the skin, and subsequent epidermal loss, identifiable as white or cloudy, fungus-like patches – particularly on the gill filaments. Mucus often also accumulates on the gills, head and dorsal regions. Gills will change color, either becoming light or dark brown, and may also manifest necrosis. Fish will breathe rapidly and laboriously as a sign of gill damage. Anorexia and lethargy are common, as are mortalities, especially in young fish"
I looked up the possible signs of columnaris for you, just in case you didn't know

 

It could be columnaris, but the lack of typical symptoms up until this point makes me think it may not be (but then again, the ulcers suggest it could be...).

Parasites can cause secondary issues, but I'm not sure that's it either. The ulcers make me think bacterial, like columnaris or another bacterial infection.

The meth blue can help with the ulcers, even if they're caused by columnaris.

 

It could be columnaris, but the lack of typical symptoms up until this point makes me think it may not be (but then again, the ulcers suggest it could be...).

Parasites can cause secondary issues, but I'm not sure that's it either. The ulcers make me think bacterial, like columnaris or another bacterial infection.

The meth blue can help with the ulcers, even if they're caused by columnaris.

Alright. Should I still go for the meth blue, then? I think I'm just confusing myself at this point.

 

I think you should still go for the meth blue, yes. Since baths are too difficult, dosing the tank would be appropriate, though personally I'd move everyone to a QT so it won't stain the silicone of your main tank.

 

I think you should still go for the meth blue, yes. Since baths are too difficult, dosing the tank would be appropriate, though personally I'd move everyone to a QT so it won't stain the silicone of your main tank.

I don't have a large enough quarantine tank for all the fish in the 55-gallon. If I did, though, I would definitely consider that. Thanks for the advice. I'll start the meth blue as soon as possible and update you on what happens.

 

Fingers crossed!

By the way, even a large tote would do.

Not sure if meth blue will kill beneficial bacteria - may be something to look into first.

 

Fingers crossed!

By the way, even a large tote would do.

Not sure if meth blue will kill beneficial bacteria - may be something to look into first.

I'll definitely do some research. I do have a black bucket that's probably about 20 gallons, a 2.5 gallon tank, and a 10-gallon tank. I might be able to use all three. I'm mainly worried about my albino rainbow shark, though. I tried quarantining her once and she jumped out right when I left the room.

 

Definitely use a lid for her container then.

 

Definitely use a lid for her container then.

Yeah. I just did some research. If I were to use meth blue, it would ruin my cycle and possibly kill plants. I'll probably just quarantine everyone. Do you think the snails will carry whatever's in my water? If that's the case, I'll have to quarantine them as well. I might not be able to find all of them, though.

 

I wouldn't worry about the snails carrying anything.

 

I wouldn't worry about the snails carrying anything.

Alright, thanks. I'll update you tomorrow. Have a good night.

 

Have you figured out the problem?

 

Have you figured out the problem?

Not exactly. I’m even more doubtful today. Everyone’s wounds are pretty much healed and the white spot on the leopard spotted danio has shrunk by a lot. I haven’t even started medication. If I were to use meth blue, I’d have to do it on Sunday because that’s when I have the most time available. Right now, I’m wondering if the wounds came from my albino rainbow shark. She tends to lunge at everyone that passes her cave, especially during feeding time. I might end up giving her away if she’s the cause. That doesn’t explain the itching, though, because she’s doing it as well (if not more than everybody else). Ultimately, I’m just confused and desperate for a solution. After all the medications I’ve used that haven’t worked, I have many doubts about meth blue working instead. I’m not sure if the stress my fish will go through is worth the outcome...

 

Meth blue isn't that stressful, but of course you don't have to do it if you don't want to.

 

Meth blue isn't that stressful, but of course you don't have to do it if you don't want to.

I really don’t know what to do. I’ll think about it.

 

We have given you a few choices. If it was me, I'd do the meth blue. They're scratching, so obviously something is wrong.