I agree.
My last batch of 10 oto's are in 7.6 to 7.8 pH water.
My water is naturally 7.6 out of the tap.
All 10 have survived for 4 weeks in my QT tank, and I just recently moved most of them into the 60G.
So the high pH has nothing to do with the oto's dying.
As everyone else said, oto's...