The blue pattern on the pectoral fins is actually on the inside of the pectoral fins of Chelidonichthys kumu and can’t be seen on the outer side. To see the blue, the fin has to be out sideways & the fish photographed from behind or above.
However I have not seen this photographed pattern of yours on the outer pectoral fin of kumu, or the Cape gurnard Chelidonichthys capensis, or the lesser gurnard, Chelidonichthys queketti. Their outer fins look dusky greeny/brown/oliveish.
However this does look like a gurnard we have seen from KZN. A spearo shot & collected one for us and it keyed out to a different genus of gurnard called Trigloporus.
It might be an undescribed species [with no species name] but we need more specimens to be sure [so that we know it is not a once off aberration]. Trigloporus have many almost vertical branches going above & below the lateral line while other triglids have a normal lateral line that looks like a slight tube through the centre of the scale.
This difference is usually impossible to see from a photograph.
Coastal fishes of Southern Africa