Corydoras Dying in Quarantine

[Vla79]

I've lost 10 out of 23 corydoras similis in quarantine since January 25th. Some of them had some redness before dying, some rapid breathing, some loss of fins and barbels, trouble swimming, but I haven't figured out a clear, consistent reason.

 

They're in a 20 gallon long quarantine tank that has been set up since December 2023 with sand substrate and a sponge filter seasoned from my display tank. Water is conditioned with prime, and I change 30-40% of the water at least twice a week. I feed mostly Sera wafers. I've tried aquarium salt up to 2 tbsp/gallon, PraziPro, Flubendazole, and Expel-P over the past two months with no improvements. I first gave the Expel-P on Thursday, March 21, followed up with a 25% water change 24 hours later, and have lost four more corydoras since that. I check the water parameters with the API master kit and parameters have been stable throughout the past two months.

 

0 ammonia

0 nitrite

20 nitrate

pH 7.4

KH 35.8 ppm

GH 53.7 ppm

Temperature 79F

 

Has anyone had success treating something similar?

 

 

 

 

 

[jwcarlson]

Are there any symptoms that you're trying to treat them for?  2 tablespoons per gallon is a lot of salt and I believe corys are very sensitive to salt.  I've gone to half that (1 tablespoon/gallon) with my discus for a week temporarily and discus are very salt tolerant.  One of the bristlenose I had in there at that dose started having fins looking really rough/eroding after a few days so I moved them.  How long have you been at that high of a salt dose?

Besides that, it seems like that's a lot of meds to be hammering them with in a pretty short period of time.  Unless there's some underlying symptom, I think I'd change a lot of water and see what happens.  How many of the original amount are still alive?  Are these adult corys or younger?  How did you source them?

[Vla79]

Thanks. The most noticeable symptoms have been redness and floating to the top of the tank, struggling to swim. Some have had white spots, but they also get the fine sand on them and it can be hard to tell. I keep the light off to try to keep stress low.

I started with 1 tbsp/3 gallons on March 6 and increased it on March 9 after floating/dying started. I wasn't sure if I was dealing with a bacterial infection and/or parasites, and thought salt would be safer than antibiotics. They are juveniles sourced from an online vendor and 13 of the original 23 are alive.

 

[jwcarlson]

How often are you changing water?  How often are you adding salt and how are you doing that?

If you've had that much salt on them for two weeks or more, I'd really suggest dialing it back (water change and don't replace it).  I can't say that I know what you're dealing with, though.  How many fish had symptoms before you started treating and how long did the symptoms occur before treating?

[Tony s]

On 3/22/2024 at 9:56 PM, Vla79 said:

2 tbsp/gallon, PraziPro, Flubendazole, and Expel-P over the past two months

Whoa, that’s a lot of anti parasitic meds to use in such a short time. Awfully harsh on little bodies back to back to back. Was there anything specific you were looking for? I think I would have maybe done a coarse if I suspected something. Then just observed them for a month in quarantine. Especially since all those meds do basically the same thing. Honestly, a month in quarantine with no meds would have been preferable. Just observing until you suspect something. After a month if nothing died, meds were probably not required. Now it’s just going to take time for them to hopefully rest and recover. I’d give up on the parasite meds for a bit. Maybe after a week give them a round of Maracyn if still losing some. It could have been bacterial in nature. But now definitely not parasitic in nature.

[Vla79]

Changing water at least twice a week. I started the salt March 6, upped it March 9, and have been keeping it at the 1 tbsp/2 gallons since then (10 tablespoons for 20 gallon tank). I would change 50% of the water and then add back in 5 tablespoons of salt, putting the salt in a fish net suspended at the top of the tank and letting it dissolve through the net.

I've had problems with corydoras since September 2023. I had a group of Sterbais from a different vendor who all died in quarantine with similar symptoms to the current ones. I didn't use any salt with that group, but I did use Maracyn and PraziPro after being advised by that vendor. I didn't know what the cause was, so I tore down the quarantine tank, disinfected with lysol, and started back up with a new seeded sponge filter in December 2023. These corydoras similis are from a different vendor. None of the medications were used prophylactically; I started after the fish were floating to the top of the tank, losing their ability to swim, and dying.

The last medication was Expel-P on March 21, 25% water change March 22, and did not add back salt.

[Vla79]

Thanks Tony. Yeah, I see that it's quite a lot to put them through. I've been reading a lot of conflicting information. I contacted an aquatic veterinarian but stopped getting responses, feeling desperate as fish keep getting sick and dying.

[JE47]

You mentioned that you had sterbias that faced similar issues in the quarantine tank did you only use the lysol to clean the tank once the sterbias had died? Someone correct me if I am wrong but I believe lysol is a household cleaner something that should not be used to clean an aquarium. 

This could be a reason your fish are dying I would water change immediately add some active carbon to water and potentially move them to a different aquarium. Do you have another aquarium available? I am sorry this happening to you hopefully we will be able to help.

Edited March 23 by JE47

[Tony s]

On 3/22/2024 at 11:22 PM, Vla79 said:

feeling desperate as fish keep getting sick and dying.

Oh yeah, understand that completely. Have had that feeling before. They start dying, you can’t explain it. And panic sets in. Ordered in a bunch from a Florida farm. Lost every one of them. Took a month to figure it out. So, yeah, I get it. lost farm animals the same way. Complete panic, but in that case big time diseases. Unfortunately, I kinda developed some callouses that way now, but not with pets. 

but horribly sometimes we have to be cool and rational about it. Trust me, very hard to do when losing animals.

yeah, I think give them time. Let them rest for a bit. Lower the salt to 1to 5. Keep your water very clean. Add some catalpa leaves for anti fungal and antibiotic properties. If they keep dying, and they might for a bit. Lots of stress on them in a couple of weeks, maybe try the antibiotics. 
 

and sorry about your loses. This hobby is great, but sometimes it sucks. The great is usually better than the bottom though 
 

 

[Vla79]

I lost a tank of fish in 2018 to Mycobacterium marinum that was confirmed through necropsy by an aquatic vet. The vet recommended using lysol to kill the myco at that time, so I used it for this quarantine tank out of an abundance of caution. It was thoroughly rinsed and dried before being used again.

Thanks Tony, I definitely agree with that. Appreciate your help.

[JE47]

When did you clean the tank with lysol? Sorry for all the questions just trying to eliminate this as a potential issue.

[Tony s]

On 3/22/2024 at 11:15 PM, Vla79 said:

so I tore down the quarantine tank, disinfected with lysol, and started back up with a new seeded sponge filter in December 2023

I assume you cleaned out the Lysol really well?  My understanding of it is that it is highly toxic to aquatic life. And doesn’t evaporate away, and may be very hard to get off the surface.
 

 

[Vla79]

No problem, I appreciate your help. I can't remember exactly, but I think the Sterbais had all passed by November, so it was probably late November or early December. I had another group of fish (same vendor as corydoras similis) that were in this quarantine tank in early January after the lysol and before the corydoras, and they are still doing fine now in the display tank.

[JE47]

What where the fish that where in the tank before the corys? It may be that they where a hardier species than the cories especially the ones you have can be little more sensitive. @Tony s do you have any suggestions for this if the Lysol is the problem?

[Vla79]

Good point. Before the corydoras similis, I had a juvenile angelfish and mini snowball pleco in this quarantine tank. No problems with them.

Edited March 23 by Vla79

[Vla79]

Good point. Before the corydoras similis, I had a juvenile angelfish and mini snowball pleco in this quarantine tank. No problems with them.

[Tony s]

I don’t really. Was just doing research on it. Hadn’t actually heard about using it to clear diseases before. But, understand about mycobacteria all too well. Costs us more money than most people can imagine. 

On 3/23/2024 at 12:01 AM, Vla79 said:

had a juvenile angelfish and mini snowball pleco in this quarantine tank. No problems with them.

Okay, good. Probably not the Lysol then. @Colu could you think on this one a bit. Give us an idea 

[JE47]

@Vla79 I feel at this point there could be a few things going on so here's a short list.

1. I think you are dosing to much aquarium salt cories are not huge fans of salt. @Colu who is our resident fish doctor has posted how much salt to use for cories somewhere around here I will try to find it and post it but I think you need to cut back how much salt your dosing.

2. You have used Lysol in the past and I think that has been impacting the cories

The solution if you have another tank available that Lysol has not been used I would move the cories there and continue to monitor see if they get better. If you have an airstone you could put in their tank that might help as well. Keep us updated and I have tagged colu who should be able to offer you some more comprehensive advice.

[Vla79]

Thanks for your help. I'll keep you updated.

[anodyne99]

Just in case it's helpful in the future, a research lab found iodine to be more effective than both bleach and hydrogen peroxide for eliminating mycobacterium marinum. Apparently there is a lot of misinformation and many old wives tales in circulation about this disease, even among  veterinary professionals. Especially concerning is that many people continue to think it's rare in the hobby, when in fact it's been found to be widespread. Iodine might be a safer and more effective choice than Lysol if you have to deal with this in the future. I really hope not, it's so awful.  Here is a link to the paper: https://www.sciencedirect.com/science/article/abs/pii/S1532045615001246

Edited March 31 by anodyne99

[JE47]

@Vla79 how are the corydoras doing?

[Vla79]

On 3/30/2024 at 11:46 PM, anodyne99 said:

Just in case it's helpful in the future, a research lab found iodine to be more effective than both bleach and hydrogen peroxide for eliminating mycobacterium marinum. Apparently there is a lot of misinformation and many old wives tales in circulation about this disease, even among  veterinary professionals. Especially concerning is that many people continue to think it's rare in the hobby, when in fact it's been found to be widespread. Iodine might be a safer and more effective choice than Lysol if you have to deal with this in the future. I really hope not, it's so awful.  Here is a link to the paper: https://www.sciencedirect.com/science/article/abs/pii/S1532045615001246

That's really interesting, I hadn't seen that before. Thanks for the link!

On 3/31/2024 at 3:39 AM, JE47 said:

@Vla79 how are the corydoras doing?

Thanks for checking in. I lost three more within a couple days of the last post, but it's been several days since the last death and everyone looks decent. I've been doing 25% water changes every 2-3 days with no salt and no meds and trying to keep stress low. Fingers crossed that the worst is over now.