Sterbai Cory dying in quarantine

[For100]

Hi all,

Wanted to pick your brains on what could be the issue here…. I purchased few fish in Aquahuna.com last week: 16 Sterbai, 4 plecos and 8 emerald dwarf rasboras.

I place the plecos and Sterbai in a quarantine tank and 7 out of the 16 Sterbai have died so far. No issues with the plecos or danios (danios are in the own nano tank).

I have no idea what could be happening. So, any guidance would be appreciated.

Problem

1. Please explain the problems with your fish. When did you notice the problems and did anything unusual happen that you think started them?

Placed plecos and sterbai in a quarantine tank about 10 days ago. I have lost 7 out of the 16 I purchased


2. Symptoms (i.e. turning dark, excess slime, not eating, clamped fins, flashing, darting, clamped gills, white/yellow/green poop, hiding, headstanding or tailstanding, white on tips of fins, rotting or fungus, blisters/white zits on fish, bloated, cloudy eyes, wounds).

When they arrived fished look small, but in good shape. I don’t see any symptoms except all sterbai are extremely skittish. I cannot get near the tank, they start swimming all over the place. Plecos on the other hand, no issues


3. What medications/ treatments have you already tried and what were the results. Include dosage and duration of treatment.

Preventive medication nitrofurancin green powder for bacterial infections and any open wounds during shipping.


Tank/Water

4. Tank size and ages, numbers and sizes of fish.

24 gallon tank placed in a different room than display tank.


5. Water change regime (What percentage and how often).

35%-50% daily water changes & vacuum bottom every day, using prime and aged water. I am using a separate water barrel to avoid cross contamination.


6. How long has tank been running? Is it bare bottom? If you have substrate, what type and how deep is it?
Bare bottom

7. Do you age your water? If you do for how long and what is the ph swing.
Yes

8. What type/brand water conditioner do you use? Do you add it to the tank or aging barrel? How much do you use?

Prime


9. Parameters and water source;

Note: Water Parameters are important in diagnosing problems within a tank. If you don't own test kits for the following information, you can purchase them, test your parameters and post this info as soon as possible.

Municipal water, same for my display tank in the living room. I am running the tank with a penguin water filter and temperature at 78F


What type of water or combinations of water sources do you use? If it is an RO/tap/well water mix, please list percentages in the mix.


- municipal water _X___



10. Any new fish, plants or inverts added recently.
Quarantine tank, all new fish same source.

11. Please tell us what you feed your fish and how often. This can be critical information for solving the problem so be as specific as you can.

Algae pellets in the morning
Flake mid day
Frozen blood worms evening

Looking from the distance, all fish seem to eat when feed them. they gather where I drop the food at the oposite corner of the tank where the filter is located.

12. Include any pictures or videos you have which shows the symptoms. If you can't add them to this post, please provide a link to them.

[Charlyc11]

My last buy from Aquahuna was 18 Sterbai and none died but I keep them at 83F with a PH between 7.2 to 7.5 even in QT. So not really apples to apples.

[For100]

Thank you Chuck. I can increase the temperature, but I don’t know if it is the problem. I read their whiskers are pretty delicate and prompt to infection. But I using a bare bottom tank. Because they are so skittish, I cannot see if they have any issues there.

Also, it is interesting plecos are doing just fine. It is just the Sterbai cories dying on me.

Did you quarantine them in a bare bottom tank?

[Charlyc11]

Yes I QT all on BB tanks and they are housed on 125G BB tank with Zebras (L046's) rainbow fish and Discus. They like the warmer temperatures on line they are all over the place with the temperature recommendations.

20231113_164548.jpg

Thank you Chuck. I can increase the temperature, but I don’t know if it is the problem. I read their whiskers are pretty delicate and prompt to infection. But I using a bare bottom tank. Because they are so skittish, I cannot see if they have any issues there.

Also, it is interesting plecos are doing just fine. It is just the Sterbai cories dying on me.

Did you quarantine them in a bare bottom tank?

[For100]

I am going to slowly rise temp to 82F from 78F.

It is a bummer, I am losing them. I cannot figure out why. Just caught a glimpse of one dying, it is swimming at the surface upside down. I am afraid, it is going to be dead by morning. Only thing unusual thing I can call out is how skittish these are. I don’t know if it has something to do or not.

Meanwhile, plecos are just doing fine in the same QT tank. So, is it safe to assume it is not my water?

[Charlyc11]

You can raise the temperature some maybe 80F you don't need to go to 82F also are they over eating? Turn light off for a few days. Is your tank cycle and have you checked for ammonia and nitrite? Can't assume anything just because no plecos died. You need to know your water.

[For100]

1- It is not cycled, but I am doing 35-50% water changes with aged water and prime to control any spikes in nitrites and ammonia.
2- As for testing the water, I have not tested my water. I can get something tomorrow morning
3- I am feeding very small amounts of food, just a little variety beCause I don’t know what they were fed before.

[brewmaster15]

If the dying started with 24 hours of receiving them its possible they either were not fasted before shipping or were just not fasted enough. Any food left in the gut in combination with cool water when shipped can lead to gut infections. Usually you can tell if the belly has a greenish or blackish look as they are dying.. it can happen with cories and plecos when fed too much vegetable matter before shipping.... its just one possibility but since its just the sterbai ..its possible..but its really hard to say.

[For100]

Thanks Al, they have been dying one every day or other day. Interestingly, they seem to be eating when given food. But they are still extremely skittish, I cannot get even near the tank when in my experience these are super peaceful fish.

Another just day last night as I said, I am down to 8 left. I must be doing something wrong but I cannot pinpoint what. I ordered water testing supply to check No2 and NH4 today, I hope I did not kill them with such an stupid error on my part.

I also dosing nitrofuracin green powder (antibioric + malachite green combo), will that address internal infections?



On the bright side, plecos are doing great in the same tank. So, I am baffled on what is happening to the cories.

[AquaticNerd]

I've never heard of Nitrofuracin green until today, so I had to look it up to see what it was about. Is this the product you are using? https://store.nationalfishpharm.com/...ofuracin-green

If so, the name seems deceptive because the active ingredients don't include malachite green at all. But I did notice that it contains "Instant Ocean Sea Salt". Maybe this is from my younger years when keeping cories, but at one point I remember folks discussing cories being extremely sensitive to salt - could this be the issue? On top of that, Instant Ocean Sea Salt contains things other than just salt - it has buffers and other major and minor elements like calcium and magnesium.

Just my two cents, as I'm not even sure the salt sensitivity was true or was more of a rumor that was going around back in the early 2000s.

[For100]

Good catch Jake, it is methylene blue not malachite green.

About salt sensitivity, first time I hear about it. The amount I use is minuscule to increase salinity in the tank. Also, I am changing more than 30% water daily, that should address any product accumulation. Dosing is 1/4 teaspoon for every 20gallons.

[brewmaster15]

Freddy I think I would stop the nitrofuracin.. you have been using it all along and it hasnt helped. Im wondering if it is possibly contributing to the losses too. Its basically national fish pharms version of the classic FURAN 2. Cories can be sensitive and its possible in your water its toxic to them. It also is going to cause you to have ammonia and nitrite spikes. I would suggest just clean water for now and see if they improve.

Al

[Discus Fever]

I totally agree I would stop the treatment completely and keep up the water changes the way you have been doing them and I believe the deaths will stop especially once you get your test kit and the ammonia and nitrite are zero. Now if the ammonia and nitrite aren't zero then that could be your culprit as well.

[For100]

Will do…. Hopefully, it takes care of it,

[Willie]

One possibility is shipping. Corydoras sterbai produces a toxin when they're stressed. In this case, the toxin may well have been stimulated by packaging and shipping. I took shipment of 2 dozen sterbais about a month ago and the shipper packaged them 2 to a bag. It was a lot of work for him, but I had no losses. This trait is not necessarily unique to C. sterbai, but it is certainly most highly expressed in this species. I also find that Corydoras cannot be crowded during shipping. If they get the slightest nick, death follows in about a week. Never have been able to nurse any of them back to health.