That is one great looking hybrid...
P. imperator and
P. chrysurus overlap along the Indian Ocean coast of Africa, and the species that I posted above are from the Atlantic coast of Africa. But I did some diving in the Seychelles not long ago and all I saw was "normal" fish...
Now, these odd lines in the hybrid you showed reminded me of a really odd looking
Acanthurus lineatus that I saw in Christmas Island (Indian Ocean) last year:
This guy doesn't look like a hybrid, just something really odd, maybe a genetic defect.