Mephisto fraserbrunneri has 6 spines and 16 soft rays in the
dorsal fin while the
anal fin has 14 soft rays. The pectoral fin has 14 soft rays and the
pelvic fin has a single spine and a single soft ray. The gill slit is long, reaching down as far as just under the lower edge of the base of the pectoral fin. The colour of the body is pinkish, other than a pale silvery patch on the abdomen and darker blotching on the upper half of the body. This species has a maximum published
standard length of . ==Distribution and habitat==