HELP....cardinal tetra dying like flies?

After cycling my tank (with 4 cories) I added 2 more and eventually also added in several stages 19 cardinal tetra.
In the beginning I lost 2 of those over several weeks (tetra).
Also added RCS and kuhlI loaches over time.
Those last one was a weak batch at the store and are left with 2.


But since a week I also have a male betta (crowntail) in my tank.
I never seen him harassing the tetra and visa versa.
Also my RCS are all happy and still allive (even have young fry of them in the tank)


But the last 4 days I lost 10 of my tetras?


Noticed 2 of them swimming strange in my tank (always had nose up and seemed to have balance problems)?
Also looked pale (less vibrant coulour). Those died later that day.


Yesterday I had another one on the bottom but still breathing....it also died.


And today when I came home 7 tetra where dead! :s


They where swimming fine yesterday and also looked great?
Kept an eye on them the entire evening because I found another one dead...


In my opinion I do not see bite marks on them?
But some of those from today their eyes where gone...
All other fish seem to do fine?


So where they sick or could it be the betta?
Would expect to also see dead RCS in the last case (and see him doing that in the evening when I am home)?

 

What are your water parameters? maybe the bioload was too much? Ive had my cardinals for a week though.

Do you know if yours were wild caught?...

I sorry, if it makes you feel better I think all my RCs got eaten... I can't see any of them.....

 

Already Checked my parameters yesterday due to the deaths that started to occur more frequently
pH 6.5
kH 4 (alwaysso low due to my soil)
gH 10
NO2 0
NO3 10
NH3 0
NH4 0

Am going to put one of the cardinals with my other shrimp in my nano tank....is there now in a cup to get used to the water...
Have 2-3 left in my main tank now.

What are your water parameters? maybe the bioload was too much? Ive had my cardinals for a week though.

Do you know if yours were wild caught?...

I sorry, if it makes you feel better I think all my RCs got eaten... I can't see any of them.....

Try to add 10 at once.
I also had half of them dissapearing in the beginning.
So I also added 10 more
Now I have 50+

Never saw my cardinal or cories attack them. Even not the betta and he could easily have taken them at that point.

 

Some of them missing their eyes seems to point to them being attacked.

 

can your nano tank handle the bioload of adding them to shrimp tank? shrimp have barely any bioload so... your BB might not be able to handle it.

there eyes are gone?? omg pop eye?
if your cardinals were not wild caught your pH might be too low bc tank raised are more for higher pH like neutral rangge...

I read that cardinals can not get tetra disease

 

It just one tetra so will keep an eye on the water parameters...
The bioload is originates from the main tank so hope the bacteria are still alive in it.

Does not seem to be showing any agrression towards te other...






Or he is allergic to shrimp.

Ph always has been this level. So do not guess that will be the cause (would have died much sooner).
Only recent change is the Betta.
Will see if more die...

Maybe I swap the shrimp from the spec3 nano tank with him.
This way I can again put cardinals in my tank.

Moved the betta to the fluval spec 3 tank,
and put the shrimp back with the rest in my main tank (except some fry I could not catch).
With some pest and assassin snails...

If the remaining 4 cardinal tetra no longer die I can be sure it was him.

Already see him chasing the fry...

 

No more dead tetras since I moved my betta...

 

Sounds like he is a very aggressive betta, better to leave him by himself.

 

Seems so.
A pitty for him since bow he has much less space to swim...
Never seen him attack the other fish or even RCS.
But where too much sudden deaths to be a disease I suspected.

Moved him to the fluval spec 3 that I bought just before I got him (as a backup plan).
Originaly I used it as a backup for my RCS (put half of them in there) in case he would eat them.
But yesterday evening I swapped them with him.
Pump system was already addapted so the water current was much less (way to powerful on a spec3).

A bit surprised since he was also in a large tank at the LFS with other similar fish (all their bettas are put like that).
Of course only 1 betta per tank.