Thanks to Jim and Morgan for, as YT nicely puts it, - shining some light on this subject!
I am assuming that the Specular slider in AquaReal
(I have it set to 60%), is therefore determining the 'Specular strength' - yes? .... And although it improves the overall reality of ALL the fish (IMO), - it would be more correct to have fish such as the Blue Tang, with little or no specular applied!
My liking for using a degree of Unsharp Mask in some situations, also seems to be partly explained here!