Just thought that I would post a couple of photos (sorry about the quality) of my new male Otorongo.
He has settled down fantastically well and after only being in the tank for 24 hours had 6 whole mussels and 3 raw king prawns yesterday and is really active up and down the sides of the tank etc.
Ross' book lists max size at 60cm, so about 24". Still need a good size tank, but these guys max out at about the same size as a motoro. I've get a female castexi thats 22", though not the otorongo variant.