How can you tell the difference between a red gurnard and a tub gurnard please?

MITCHELL SAUNDERS, BY EMAIL

DL says: Small red and tub gurnards are surprisingly easy to tell apart, even though both species are red.

The tub gurnard has a vivid lilac fringe to its pectoral fins, as shown (below), while red gurnards do not, and are usually a much brighter, vivid red.