The Lionfish, of the genus pterois, is “characterized by conspicuous warning coloration with red, white, creamy, or black bands, showy pectoral fins, and venomous spiky fin rays.”
Apparently their bright colorations, contrasting stripes and fans of projecting spines are a way to warn other species of their defensive abilities. It is unclear if these signs of danger are attractive to the opposite sex.
It may not come as a surprise, given that other species, particularly homo sapiens, seem to be attracted to the “thrill of danger” when it comes to the opposite sex. This article from Psychology Today cites evolution to explain “Why Good Girls Like Bad Guys.” And a bestselling book was written by a woman on “Why Men Marry B*tches.”
At least for the Lionfish, mating is done with the female releasing egg masses into the water, which the male fertilizes before floating to the surface. Potentially a “no-touch” affair.