Nice and very rare find, what I call a "black bufonis" species, not the usual and smaller orange w/ brown banded variety and likely to be a sub-species, not a true bufonis but extremely rare. I've only seen one and that was mine that I had for many years, acquired at 6" and grew to 12" over a few years. Here' pic's of the one I had:
Good eye Viktor, the bottom photo I posted was a mistake and was of my c. apurensis the day it was sold, filed in the wrong folder of my catfish archives. Sorry to mislead anyone!
Here's another photo of the correct species..