Courtship and Spawning in Anthiinae
I laboured hard to actually work out which species this is, eventually I settled on that it is in fact an intensified/nuptual colouration of the Squareblock Anthias, (Pseudanthias pleurotaenia) - quite a special one in the case of the male it would seem.
I did wonder if it was either the Aurora Anthias, (Pseudanthias calloura) or Shen's Anthias, (Pseudanthias sheni), but in the case of the first the range is wrong as well as the female colouration being different (amongst other things), and the second having an incredibly small natural range. Morphologically, the second is closer - but it's limited to a tiny region off of Western Australia, whereas this is listed as having been taken off of Japan.
Anyone got any insight into it? I'm pretty confident in the ID, but certainly not 100% by any means.