I have seen him doing it against the glass panels of my tank but it's very rare that I didn't pay much attention to it. I would suspect that my tig may have also used parts of the old driftwood, but because it wasn't a single piece of driftwood, but pieces of them tied together in my attempt to recreate the mangrove swamp roots look, that may also explain why the parts that were in contact with the base of the tank moves position now and then. Generally, I didn't notice my tig doing that in the previous tank.
I do notice since when I first bought this Tig (my time with the previous tig was too short to have observed any behaviour because I made a fatal mistake through medication) that if it catches a prey it cannot immediately swallow, it will always go to his home or 'home area' in the case of the previous set up. Which makes sense as their natural instinct to be in safety while the attention is on swallowing the prey.
I'm not sure why Brachyplatystoma has evolved to have such peculiar heads, but as evolution is usually adaptation to serve as key to survival of the species, this could be a reason for such broad bony head. My tig also does not seem to suffer much pain from banging his cheek/snout area sideways in the attempt to knock out the prey as evidenced by the actions being repeated after several minutes.
Since the lfs where I purchase my feeders always come in irregular sizes, I'm sure I'll have lots more opportunities to observe this behaviour.
Meanwhile, I'll continue to add koi clay to my tank on a weekly basis and then maybe after a few months, I'll stop using it for a period to see if the increase in appetite is really linked to the koi clay which was something found while cleaning out the ex koi pond equipment area since we have already demolished the pond and reuse it as garden some years back.
