And then we call it a Sarcastic Fringehead:
Source: Pixdaus
And they have a special talent, as NewScientist (10 March 2018) tells us:
SARCASTIC FRINGEHEADS have more of a temper than your average fish, but it isn’t a sharp tongue that their rivals face: it is their gaping, fluorescent mouth.
When threatened by another male, the fish opens its mouth about as wide as its head, displaying an outer and inner row of teeth. This effort is intended to show other fringeheads that “I’m bigger than you and you shouldn’t come into my area”, says Watcharapong Hongjamrassilp at the University of California, Los Angeles.
Which just accentuates the coolness.
