Hello,
My sister and I are having the same issue, but we have owned our 2 pictus catfishes for over a month now and only 1 of the 2 catfishes are displaying these symptoms (also it is not hugging the bottom, it is swimming mid tank)
Our tank is a 20 gallon tank and it shares its home with our other heathy pictus, large goldfish (about 4 inch feeder goldfish), 2 minnows and 2 plecos (one albino bristle nose and one rubber lip). All the other fish seem fine and I never see them pick on each other (they do seem to be avoiding the sick pictus as of today when the symptoms became noticeable).
They get fed twice a day, usually flakes, but once a week they get blood worms or an algae pellet. I know twice a day feeding might seem like a lot but none show signs of bloat and we only give a little at a time (plus we do once in the morning for our day feeders and once at night for our night feeders)
We check water levels regularly, always fighting nitrate levels (we have pellets in our filter for the nitrate, but they get fresh water at least once a week) and water is hard (and sometimes slightly acidic), but nothing new.
We are going to do a 25-50% water change tonight, but since all the other fish are fine currently I am concerned water environment is not the cause of this behavior. We have had the goldfish and minnows for over a year (they were meant be crayfish food, but our crayfish decided she liked those 3 and when she passed we got the catfishes and plecos, things had been fine until today).