Julii Corydoras Continually Dying Off

[joemonkeaquat]

The 12 corydoras I had purchased earlier this week are now down to 6.
Tank
What is the water volume of the tank = 90 Gallons
How long has the tank been running = 4 Months
Does it have a filter = Yes, an eheim canister + a wavemaker
Does it have a heater? = Yes
What is the water temperature? = 26 Celsius
What is the entire stocking of this tank? (Please list all fish and inverts.)
An Angelfish
Albino Bristlenose Pleco
3 Otos
6 Julii Cories
16 Silvertip Tetras

Maintenance
How often do you change the water? = Once a week
How much of the water do you change? = 20%
What do you use to treat your water? = Seachem Prime
Do you vacuum the substrate or just the water? = Only the Water

*Parameters - Very Important
Did you cycle your tank before adding fish? = Yes
What do you use to test the water? = API Freshwater Kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 0-5ppm
pH: 7

Feeding
How often do you feed your fish? = Daily, Might Fast Once a Week
How much do you feed your fish? = No idea how to quantify that

Illness & Symptoms
How long have you had this fish? = Less than a week
How long ago did you first notice these symptoms? = over the last two days they've appeared more lethargic + breathing more rapidly
Have you started any treatment for the illness? = no, only additional water changes, which I'm suspecting to be the cause at this point
Was your fish physically ill or injured upon purchase? = only one, had the start of popeye
How has its behavior and appearance changed, if at all? = less active, faster breathing

Explain your emergency situation in detail.
I can't recognise any issues with my water parameters as cause for this issue. None of the dead fish have visible lesions or marks. Corydoras appear to be the only fish in the tank effected. The remaining fish seem less effected than those that haver already died, but the first four I lost had happened overnight and I saw no indication of illness before hand.

 

[A201]

New fish are often suffering from unseen ailments contracted somewhere along the way from the hatchery to the vendor. The added stress of being introduced into the customers tank can be the last catalyst leading to sickness & death.
Despite your good water parameters, you might up your weekly water change to 35% - 50%.
Water chemistry in new set ups are notoriously unstable.
The go to guy for Corydoras is DoubleDutch

 

[EnlightenedOne]

I've had two False Julii Corydora die on me as well. I noticed their dorsal fin was lowered and body paler. Other than that no signs of illness. I had one die a week ago and one randomly a few days ago. I dissected one to see if it was internal. They had some kind of internal bleeding. They were always pale when I got them. The remaining three are still doing well but from what I read Julii/False Juliis are inbred to **** and may be weaker stock. If they are wild caught they are stunned with electricity or drugged then shipped in oxygen filled bags. Scientists noticed they then develop red blotch disease and died randomly. Owning one of these for a month is considered success if that's the case. Which is sad because all my water parameters are excellent and no other fish show those kind of symptoms. They just die over night. When you scoop them out look at their bellies and see if you see some red blotches on their bodies. Might be an internal infection. I usually scoop those lighter colored and lethargic out. Or if I see red splotches on them.

Also True Juliis are pretty rare, where did you get them?

 

[joemonkeaquat]

New fish are often suffering from unseen ailments contracted somewhere along the way from the hatchery to the vendor. The added stress of being introduced into the customers tank can be the last catalyst leading to sickness & death.
Despite your good water parameters, you might up your weekly water change to 35% - 50%.
Water chemistry in new set ups are notoriously unstable.
The go to guy for Corydoras is DoubleDutch

While I agree the fact that they were new could be a contributing factor, I find it hard to believe 50% of them would be effected, especially after a day or so of acting fine.

I've had two False Julii Corydora die on me as well. I noticed their dorsal fin was lowered and body paler. Other than that no signs of illness. I had one die a week ago and one randomly a few days ago. I dissected one to see if it was internal. They had some kind of internal bleeding. They were always pale when I got them. The remaining three are still doing well but from what I read Julii/False Juliis are inbred to **** and may be weaker stock. If they are wild caught they are stunned with electricity or drugged then shipped in oxygen filled bags. Scientists noticed they then develop red blotch disease and died randomly. Owning one of these for a month is considered success if that's the case. Which is sad because all my water parameters are excellent and no other fish show those kind of symptoms. They just die over night. When you scoop them out look at their bellies and see if you see some red blotches on their bodies. Might be an internal infection. I usually scoop those lighter colored and lethargic out. Or if I see red splotches on them.

Also True Juliis are pretty rare, where did you get them?

These guys are False Julii, I should've specified. I'm yet to have seen red blotches on them but have definitely heard of that. I got a few pictures of the survivors, they definitely seem quite a bit more active today. I did notice one had a slightly torn analfin but I'm hoping they'll all make it

 

[DoubleDutch]

What exactly do you feed them and what is the substrate in the tank ?

 

[joemonkeaquat]

What exactly do you feed them and what is the substrate in the tank ?

They've only been fed live blackworm so far. It's just a sand substrate
Seems I've lost another. One has also started flashing around the tank, then goes stiff and floats down to the bottom
Genuinely confused, the flashing cory has died now as well. No other fish in the tank are showing signs of stress. I've tested again and nitrate is still barely even showing up. I don't really have a clear course of action here

 

[DoubleDutch]

And ammonia + nitrites are 0,0 ?

What do you use as conditioner ?

 

[joemonkeaquat]

And ammonia + nitrites are 0,0 ?

What do you use as conditioner ?

Yes, they both are. I Use Seachem Prime
These are the params

 

[DoubleDutch]

Quite weird. The fish looks great.

I'd inform the LFS and ask how the remaining fish are doing. Maybe we're searching for a clue in your tank though there is something wrong in the whole shipment.
Could you please place some pics of one of the remaining fish ?

 

[joemonkeaquat]

Here are two of the remainders I found. They're acting polar oppositely. The first has stayed in that same position all day, the second has been constantly surfing the glass and moving around.

 

[DoubleDutch]

Here are two of the remainders I found. They're acting polar oppositely. The first has stayed in that same position all day, the second has been constantly surfing the glass and moving around.

They look great. They can show both kinds of behaviour when new but both should on some point show the behaviour of the latter one (adapting).

Think we can eredicate worms, parasites, etc... Bacteria (maybe in the blackworms) could be as well as chloramine or so.

Did you get them from nearby? Are waterparameters the same as in the LFS ?

 

[joemonkeaquat]

They look great. They can show both kinds of behaviour when new but both should on some point show the behaviour of the latter one (adapting).

Think we can eredicate worms, parasites, etc... Bacteria (maybe in the blackworms) could be as well as chloramine or so.

Did you get them from nearby? Are waterparameters the same as in the LFS ?

Yes they were from a nearby LFS, however I didn't think to ask the parameters they were being kept at there. The lights are out now so I'm hoping to have no more losses in the morning. Even so I still can't find a reason behind this.

 

[DoubleDutch]

Yes they were from a nearby LFS, however I didn't think to ask the parameters they were being kept at there. The lights are out now so I'm hoping to have no more losses in the morning. Even so I still can't find a reason behind this.

No it is quite weird. Maybe is feeding something different an idea (just a try)