Hi,
Sparcs, you said, a falling ph, under 6,5 is a indication of No²/³
I adjusted my water with peat and rainwater of a ph of 5,5. My 134er likes it!
Your catfish seems to be a Liposarcus pardalis, in my opinion he needs a realy big tank!
150cm should be a minimum!
I wish you and your catfish...