I agree with its great, remarkable closeness to Pterodoras granulosus and I agree that it is not it. Very likely it is a Pterodoras.
Most obviously to me, granulosus has far, far more aggressive scutes along its flanks, bigger, longer, with sharp hooks. This guy's armor is much more subtle and blunt.
The body shape and the eyes also point away from a granulosus.
That's all I can say without looking carefully through known doradiids or known Pterodoras species.
I've searched though planet catfish. All 68 species in that family. Nothing has come up. Unless it was one of 4 pages that has no picture.
The closest fish it looked like was the pterodoras lentiginosus. Although there is still a few features that makes this not that's fish.
Everyone ive asked is stumped, apart from the little information ive managed to find (as above).
It's deffiantly an intreasting fish.