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Lethargic pygmy corydoras


andieb
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Hi everyone, 

Last night I added 8 pygmy corydoras to my 20 gal long tank, which already had 3 apple snails and 5 ghost shrimp. 

I tested the water parameters before adding the fish and also just now and they haven't changed: 

pH: 6.5-7.0
Nitrates: 10
Hardness: 140
Nitrite: 0
Ammonia: <0.02
KH/Buffer: 20
Water Temperature: 78

I acclimated the corys for 50 min before adding them by pouring out some water and adding a bit of tank water in small bits. 

Anyways, even before I added the fish to the tank I noticed that one wasn't moving much and wasn't responding to his surroundings consistently. He swam around when I first added him but then he quickly went back to being lethargic, sitting on the bottom motionless but breathing quickly. 

This morning I couldn't find him. Tonight I still only counted 7 fish but then all of a sudden he swam out from a hiding place, but he seemed really uncoordinated and almost immediately swam back down and hasn't moved since. He's almost lying on his side now but he's still breathing. 

Everyone else is acting and looking healthy. 

I'm not sure what to do. Any ideas for what might be wrong with him? Any suggestions for what to do are really appreciated! 

I have a second tank that I only just set up, but it just has sand and nothing else in it, except a brand new sponge filter and a heater. I haven't cycled it yet but I have seachem stability and I could put the intake sponge from my established tank in the new tank. I can also take a plant or two to give him a hiding place. I honestly think he's not long for this world. I really don't want the sickness to spread to the others though. Should I move him to the other tank? I also stupidly just realized I don't even have a fish net. AHH

Thank you so much for your help! 

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Ok, quick update. I got really worried about him infecting the others cause they kept swimming close to him. So I did everything I said in my first post - put the intake sponge from my established tank into my new tank right beside the sponge filter, made a hiding place for him, and added seachem stability and seachem prime (to detoxify nitrites). I picked him up really gently with my hand and put him in the new tank. I also added some food in case he comes around a little. But honestly I think he's practically dead.

Is this common? Do you think my other first might need preemptive treatment? 

Edit: once he was in the quarantine tank, I could look at him carefully and I saw he has a lesion on his head that looks like hole-in-the-head disease or head and lateral line erosion (HLLE). Should I treat all the fish, the sick and the ones in the main tank with meds containing metronidazole?

Any advice is appreciated! 

Edited by andieb
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Hi guys, so unfortunately, the cory died. Now I'm noticing that my other corys in the main tank are doing an odd behaviour, I think it might be "flashing". I'm wondering if it could be linked to what killed the first first. 

I uploaded a video on youtube, I promise I'm not promoting anything, here's a link to a video of the behaviour. The behaviour starts at around 2:50.

 

Is this what they mean by "flashing"? My KH is low, around 20 ppm, could be it linked to that or could it be a parasite? 

Thanks again for all your help! 

Edited by andieb
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I would say they have internal parasites, but I can't be certain. Mine do this a lot (they've done it for several months sporadically before me realizing that it could be a parasite. Thankfully, I haven't had any deaths yet) so I treated them with General Cure, but it hasn't worked. I plan on treating them again.

So I can't be certain of what to treat your's with, but I hope this helps to give some advice on your situation.

P.S. Those are not pygmy corydoras (Corydoras pygmaeus), but the pygmy salt-and-pepper catfish (Corydoras habrosus). If I recall correctly, they are tank-bred/raised and not mostly wild caught, but I could be wrong.

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1 minute ago, CorydorasEthan said:

P.S. Those are not pygmy corydoras (Corydoras pygmaeus)

Hi there, 

Thanks for the advice! I'm going to do a bit of research into what the parasite could be and I'll pick out a medication.

And yes, one of the corys is bigger than the others and I thought it was a salt and pepper, even though I technically purchased "pygmy corydoras" but it was curb side pick up so I didn't see what I had got until I got home. I thought the smaller ones could be pygmys but now that you mention it their fins are stripy and look more like salt and peppers... interesting. 

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Just now, andieb said:

Hi there, 

Thanks for the advice! I'm going to do a bit of research into what the parasite could be and I'll pick out a medication.

And yes, one of the corys is bigger than the others and I thought it was a salt and pepper, even though I technically purchased "pygmy corydoras" but it was curb side pick up so I didn't see what I had got until I got home. I thought the smaller ones could be pygmys but now that you mention it their fins are stripy and look more like salt and peppers... interesting. 

Oh sorry I didn't mean to confuse the different cories. The ones you have are the Corydoras habrosus, the salt-and-pepper pygmy cory (also called the dainty cory or venezuelan pygmy cory). The true peppered cory, Corydoras paleatus (also known as the paleatus cory or the salt-and-pepper cory as well) gets much bigger I don't think you have those. Here is a picture of the peppered cory (Corydoras paleatus) for reference. (The one in the middle with the gray-blue color is the peppered cory)

764878137_FeedingFrenzy2.JPG.b6860f9c8eeed254a22d9ee65d204594.JPG

Now here is a picture of one compared to the true pygmy cory (Corydoras pygmaeus), which is slightly smaller than the Corydoras habrosus you have.

20201225_094156.jpg.44cbdcf9d0e2b9f354f7a99d725ca9a8.jpg

Again, sorry for the confusion. I hope this helps!

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  • 3 months later...

Hi I am curious to find out how this situation turned out. Was it a parasite and did they survive? My Pygmy Corydoras have been fine for while and my older ones are large but light in color recently. The newer crew I noticed a few of them stayed small and dark in color, I lost two a while back. Today I have another small dark in color dying. I put it in my quarantine tank just a few minutes ago, added salt, Pimafix and Melafix. Temp is at 76 degrees. Perimeters are zero for ammonia and nitrites and nitrates, pH is around 8. Thanks for any advice. I think he's going to die soon but curious to know what might have been wrong. I had them for a month or so and they didn't grow much at all, stayed real dark, while the others grew nice and big and are light in color. Might be females surviving and males dying? Unsure. Thanks!

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On 6/29/2021 at 2:50 PM, Breezy said:

Hi I am curious to find out how this situation turned out. Was it a parasite and did they survive? My Pygmy Corydoras have been fine for while and my older ones are large but light in color recently. The newer crew I noticed a few of them stayed small and dark in color, I lost two a while back. Today I have another small dark in color dying. I put it in my quarantine tank just a few minutes ago, added salt, Pimafix and Melafix. Temp is at 76 degrees. Perimeters are zero for ammonia and nitrites and nitrates, pH is around 8. Thanks for any advice. I think he's going to die soon but curious to know what might have been wrong. I had them for a month or so and they didn't grow much at all, stayed real dark, while the others grew nice and big and are light in color. Might be females surviving and males dying? Unsure. Thanks!

If there not growing well and on the small side it could be internal parasites as most pygmy Cory's are wild caught I would treat for parasites with paracleanse

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Thank you for your response. I've moved it over to quarantine and treating it now but doubt it'll make it. I ordered their "tank bred" as opposed to their "wild caught" but I also received a Rasbora in which I didn't order as well. So I'm wondering if I got a mix of wild and tank bred Pygmy Corydoras now since it seems stock picking process wasn't carefully or thoroughly looked at. Also I treated all of them before adding them to the community tank. Treated them for and kept them in Quarantine for 3 weeks beforehand. So I dunno. Unless it's a genetic issue, but I think you might be right in that maybe I possibly received a few wild caught instead of tank bred. I contacted the breeder company for help with my issue as well. Thanks again!

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Hi @Breezy! To clarify, do you have corydoras pygmaeus or corydoras habrosus?

I ended up losing 4 habrosus total to fungus and lethargy, so I only have 4 left but they've been healthy since. I have 2 females, which are very large and round, and two males, which are small and slender, almost half the size of the females. All are similar colour, however the turn pail when they're stressed. When ever they're pail, I try to figure out what could be causing it. I never found out for sure what caused the first 4 to die or why the remaining 4 survived, but I made some changes to my set up to try to stop the deaths. 

These are the changes I made: 

- I added a small sponge filter to help cycle the water down near the substrate 

- Gravel vac the substrate really carefully every week 

- Turned the temp down to 76 C since fungus grows more at higher temps 

- Added aragonite to my filter to stabilize the pH 

Ultimately tho, my theory for what happened was that this species is just really delicate and sensitive to changes in water parameters. 

If you also have habrosus, it's possible that the smaller ones are males and the bigger ones are females, but my males and females are the same colour. I'm not sure why yours might be dying but here are some thoughts. Check their barbels to make sure they aren't worn down. If the barbels are worn down, it could interfere with feeding and might explain why some of yours are small and maybe the one died from not getting enough food. Do you have swings in your parameters? Like for example, does your pH change gradually between water changes? When you do a water change does your pH change? What is your KH? How much do your nitrates increase between water changes? 

I suggest trying 2-3 tsp of aragonite in your filter if your KH is low and your pH is swinging. If you're nitrates go above 10-20 between water changes I would say, either do more frequent water changes or try adding seachem stability, water lettuce or other plants that are known for taking up a lot of nitrates. 

 

 
Edited by andieb
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