All of my new Kuhlis died within a week?

[CiwisAquatics]

So exactly a week ago, I had bought four more Kuhlis for the two that I have had (those two are doing very well right now). I lost the first of the four on Sunday. Then on Monday, I had noticed another one of them having seizure like movements, then laying on its back or sides. I got up this morning to go check on them, saw 2 of the remaining 3 dead, checked underneath the driftwood & saw the final one was gone as well.
It's a 30 gallon tank, with two 20 gallon sponge filters. The only stocking at the time was a single female Betta, 4 Pygmy Corydoras, & the 6 Kuhlis.
Parameters: Ammonia-0, Nitrite-0, Nitrate-5, PH-6.7, Temp-79/80
There were no salts or medications in the tank

 

[Salem]

Do you happen to know what the parameters for the water they were previously in? Did you quarantine them?

If the parameters of their previous tank were different enough from your own its possible that could have caused it but I suspect that would have happened a lot sooner. My only other thought at the moment is that they could have been ill or had some sort of parasite.

 

[CiwisAquatics]

Do you happen to know what the parameters for the water they were previously in? Did you quarantine them?

If the parameters of their previous tank were different enough from your own its possible that could have caused it but I suspect that would have happened a lot sooner. My only other thought at the moment is that they could have been ill or had some sort of parasite.

I wanted to mention this in the post but I did slowly acclimate them to my water before adding them to the tank & parameters were pretty similar anyway, so it probably wasn't related. I was going to quarantine them before putting them in but it completely skipped my mind before I put them in the tank.