Fish in QT scratching, not ich, not velvet, etc.


Hello All.

Sorry in advance for the long winded post. I wanted to try and get as much information as I had in the post to eliminate some of the basic questions!

I have some panda corydoras in QT currently. They're kind of a mismatch of random symptoms but I'm mainly concerned about one: Out of the 11, there's 1 that has constantly scratched itself on the bottom of the tank (bare bottom) since receiving the batch.

There is also a different one that consistently has red gills, but it could just that there isn't much pigment in it's skin (I'm not sure if I'm explaining that well). Another couple don't seem to eat well with a variety of foods and although they don't seem malnourished I wish they had put on some extra weight. I'm currently out of ideas on what could going on be an open to suggestions.

Here has been my thought process the last two weeks:
  1. When I first noticed the scratching a few days in, I waited to see if there were any signs of ich, but so far after two weeks there has been none.
  2. I thought perhaps "scratchy" and "red gills" could be a result of a water quality issue (even though I was doing water changes every two days). Water parameters are a constant 0-0-5ish with a cycled sponge filter.
  3. Maybe "scratchy" and "red gills" could be from chlorine/chloramine burn if I didn't put enough dechlorinator into the tank. So far two weeks later there isn't a difference after 7+ water changes.
  4. I thought maybe the "picky eaters" were suffering from internal parasites. Planned on a course of Paracleanse (active ingredients metronidazole and praziquantel).
  5. Coincidentally, in my main tank I have 4 panda corydoras that have had fin rot issues constantly since I got them a year ago. They will go through periods of losing fins for a couple of weeks, to being fine for months, back to losing fins overnight, etc (it's not a water quality issue and it's been something I constantly complain about in different threads, sorry haha). I woke up last weekend and I saw one of them losing fins and I figured, "hey, might as well treat them in the QT for fin rot, just in case there's something bacterial going on with the new arrivals." Two birds with one stone mentality.
  6. I plopped the 4 "clean" pandas into the QT and started a course of Maracyn (active ingredient erythromycin) along with Paracleanse. Decided to fast the whole time they were being medicated.
  7. "Scratchy" has still be scratching this entire time and I checked water parameters everyday just in case I nuked the biofilter, still 0-0-5ish. Coincidentally, "scratchy" has the shortest barbells of all the pandas I received.
  8. The first 3 days of meds, one of the "clean" pandas got incredibly red gills and then started having swim bladder issues. The swimming issues only lasted a few hours each day and were after meds were dosed each time. Today is day 4 and "floaty" didn't react with swimming issues (yay) and the red gills aren't as... red.
  9. Overall "red gills" isn't as red as before, but still slightly pink (not sure if actually less red, or more pigment in the skin now).
  10. The "picky eaters" I can't tell if there is a change since they've been fasting. I haven't seen any odd poops in the tank though (barebottom).
  11. Tomorrow is day 5 of meds and the plan is to start doing daily water changes on day 6 and keep them in the QT for a few days while I "beef them up" with food. But I'm still concerned about "scratchy" since I'm out of ideas what could be affecting it.

Are there any "common" illnesses that I might be overlooking that can cause scratching? Ich... I don't think so. I've treated ich before and after two weeks I'd expect all of the fish to be blasted with salt by now. Velvet... same thing, had it before and so far no symptoms. Water quality... clean and stable pH. Injury... I don't see anything. Flukes... I don't think gill flukes, the gills are not actually red and doesn't seem to have any exterior issues... Also a full course of Paraclease. Bacterial... I don't think so and hopefully Maracyn and Paracleanse took care of that (the fin rot stopped on the "clean" ones... for now, lol). I'm fine if he's just an itchy fish in general but I'd hate to overlook something and wreak havoc in my main tank.

Thanks for taking the time to read this novel!

Edit: shortly after posting this one of the newbies started floating at the surface on its side. It’s still alive. Is there any cases of Maracyn or Paracleanse causing buoyancy issues? The meds definitely changed the viscosity of the water (can tell by all the bubbles).


Shortly after posting this one of the newbies started floating at the surface on its side. It’s still alive. Is there any cases of Maracyn or Paracleanse causing buoyancy issues? The meds definitely changed the viscosity of the water (can tell by all the bubbles).

Edited the original post with this info.
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Take a deep breath & relax. Its not a good idea to blindly medicate.
Chances are the Corys are flashing due to slight water parameter differences from constant water changes.
The exposure to the listed meds might be adversely affecting the noted cory.
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I haven’t had a chance to update and wanted to do so in case my specific experience can benefit someone.

Everyone survived quarantine and have been in the main tank for about a week.
  • Fish stopped flashing/scratching during medication. Still no obvious signs of ich.
  • Viscosity of the water definitely played a role in the buoyancy issues with the fish. Even though the dosing instructions don’t recommend water changes, I would do so before each new dose.
  • Fin rot cleared up... hopefully for good this time (doubt it, lol).
  • Fish with red gills are fine. In the display tank with a brighter light it’s now obvious they’re just “pigment deficient” and need to darken up. Most have already darkened up since receiving them.
  • The picky eaters finally started eating after the meds. Unknown if they actually had internal parasites. No weird poops but appetites seemed to get jump started in quarantine after. Still have one newbie that’s having a slow time recognizing food (pellet, flake, wafer, bloodworms).
Hopefully someone experiencing the same stuff can find some solace in the fact that they weren’t/aren’t the only ones lol.

Take a deep breath & relax. Its not a good idea to blindly medicate.
Chances are the Corys are flashing due to slight water parameter differences from constant water changes.
The exposure to the listed meds might be adversely affecting the noted cory.
I agree about not blindly medicating and it’s the first time in a decade that I have used meds. However I don’t feel I was as there was active fin rot and after two weeks of not eating or putting on weight it was time to try something.

I have to respectfully disagree about the frequent water changes causing fluctuating parameters. I’m in the camp that believes small frequent changes cause less fluctuations than one big one. With that said, I only do that in quarantine to provide the cleanest water possible and only do large weekly water changes in my main tank.

Thank you for taking the time to reply.
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Well it took awhile to diagnose, but I think I'm finally on the right track thanks to finding CindiL's old thread about columnaris: Columnaris Symptoms And Treatment | 263058 | Freshwater Fish Disease and Fish Health

Not long after putting the pandas into my main tank, the 4 "year old" ones immediately got fin rot again. I debated on dosing the whole tank with Maracyn (erythromycin) as it's quite large and would cost a good amount of money. I decided to wait and see if they would clear it up on their own (as they have done off and on the year I've had them). I woke up the next morning to half of the newbies showing signs of a bacterial infection. Decided whatever was causing it was already in the display tank even though it wasn't affecting all the fish.

I began a course of Maracyn in the main tank a few days later after receiving it in the mail. I slowly started losing the newbie pandas one or two at a time. Some of the deaths had signs of bacterial infections, some didn't and were "sudden." Around day 3 I noticed one of my healthy "year old" pandas started showing signs (oh no at this point, whatever is in there is virulent enough to get the healthier ones). The symptoms on this panda was bacterial infection around the fins and also around the mouth.

At this point the symptoms all finally started clicking as I recalled CindiL's thread during my searching. Some fish gasping for air in a well oxygenated/circulated tank, paleness, swim bladder issues, scratching without signs of parasites, signs of bacterial infection on body and fins, and now mouth. I only wish that one of the fish had developed symptoms on their mouth earlier on and it would have helped with my diagnosis. I'm also assuming it made it into my quarantine tank as the spong filter came from my main. However as I read it, it sounds like it's always present in the water (as all bacteria and viruses are in life) and perhaps the stress lowered their immune systems enough to be susceptible.

Realizing that columnaris is typically a gram negative bacterium, I went online to find some Maracyn 2 (minocyline). Unfortunately when I made the purchase, it was July 2 and with the 4th coming up shipping was slower than preferred.

After finally getting Maracyn 2 into the tank, I still had losses, but so far I haven't had any since day 3... today is day 5. All of my panda corydoras are showing symptoms currently however none look "physically worse" knock on wood. In all I lost 9 out of 12 newbies and 1 of the "year old" pandas that had chronic fin rot. I'm prepared for a second round of Maracyn 2, although my wallet isn't.

Side note, all of the rasboras and hillstream loaches in my main tank look fine so far. Fingers crossed whatever blazed through the corydoras isn't as virulent with them.

Hopefully someone with the same symptoms going on in their tank can use this thread to point them in the right direction.
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I finished the second round of Maracyn 2 yesterday. Lost one panda at the beginning of this round which was surprising since it was a smaller one that didn’t have any symptoms while I haven’t lost any of the “horrible looking” ones. Half of them look healthy and symptom free though which is great.

I netted out 6 of them to place in quarantine to continue treatment. It was quite the exercise in patience trying to get them out of a planted tank. You’d be surprised how fast a corydoras can go with a nub for a tail.

Even though the dosing instructions say to take a day off I didn’t this time. Between round one and two some of the worse off pandas seemed to relapse pretty bad having the interruption in antibiotics. I thought I would lose three of them but they pulled through.

I switched it up this time and in addition to Maracyn 2 I also purchased some Furan-2 as mentioned in CindiL’s thread. After 24 hours the 6 in quarantine look to be responding even better/quicker than before. To be fair they were looking better at the end of the previous round so they could just be on the mend anyway.

Side note, it was very pleasing finally being able to give the main tank a good cleaning, filtration included. The meds in the water add their own unique funky smell lol.
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Short update. 3 of the 6 looked good after the third round of Maracyn 2 and Furan-2. I put them back into the display. One that was missing the top half of its tail is showing a lot of regrowth surprisingly. Another that had the tip of its tail gone had some slight regrowth, just enough to make it symmetrical. The third one that went back in was one of the new juveniles. Unfortunately it stopped eating and it passed a week later without any other signs of columnaris.

The three in quarantine still did not do so great. I hadn’t recalled the one juvenile in there eating at all for a couple of weeks and it passed. One of the year old pandas with fin rot had it cleared up but also stopped eating and passed a few days later. The remaining one had severe fin damage and got a secondary fungal infection. I tried API Fungus Cure which cleared it up well but left the panda in horrible condition. Outcome doesn’t look great but trying to get it to keep eating in clean tank water free of meds.

Some concerning observations... I’ve noticed some of the pandas with slime coat growths again. I noticed this happening about a month before the columnaris outbreak the first time. This time around I will be pulling any that actually look like they’re showing symptoms to stop the spread.

I’ve also noticed some of them scratching on the substrate occasionally. I’m not sure if this is a new symptom or just a result of their skin still being sensitive/irritated after being wrecked by columnaris. So far no symptoms other than that though.

I originally started with 11 panda corydoras and hoped to double the shoal in my new tank. Now I’m at 9 total which includes only one survivor from the new batch of juveniles. But on a bright note, I saw a panda fry for a brief moment! My wife and I saw an egg floating around a couple of weeks ago before it got eaten. It surprised me that they were happy enough to spawn while being hit with meds lol. Hopefully this fry will find some decent places to hide until it’s larger.

The other fish in the tank are 24 Rasboras and while I know they’re generally hardier, they haven’t had any columnaris symptoms or other. Still trying to figure out how the corydoras are having such a rough time.
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