...My immediate guess is that this is a one-off, a specimen which colouration has not developed normally. It would be really cool if it was a new species though
I think your former guess is probably correct, but like you, I think it would be very cool if it was a new species...
A mouth/dentition pic is necessary in order to identify the genus....now it is just geussing....
You're right, it would certainly help. Once it has settled in properly, I shall catch it and get mouth shots as I'll be an eternity if I wait for it to appear on the front glass.
A good picture of the dorsal and the adipose fin will maybe give it a positive ID it to the genus Oligancistrus. A dorsal fin that is felt down will touch the adipose fin of an Oligancistrus.
Any way, it is an extremely nice fish you got there.
Decent side shot added to the required photograph listing also and thank you for the compliment, I agree, a lovely looking fish.