Goniobranchus fidelis (Kelaart, 1858)

Distribution: 

Sometimes locally common in the Solitary Islands Marine Park. Found throughout the Indo-West Pacific, generally classed as uncommon.

Ecological Notes: 

Found on food source on walls and reef edges down to 24 m. Feeds on red encusting sponge.

Additional Notes: 

Specimens photographed here considered to be a regional spotted colour variation of G. fidelis known to range only from northern New South Wales to the southern end of the Great Barrier Reef. Number and size of red spots is extremely variable, but the spots are always symmetrical. The black gills and rhinophores distinguish this species from Goniobranchus splendidus. Grows to 25 mm.

References: 

Australian Museum, Sea Slug Forum. http://www.seaslugforum.net/chrofid1.htm. Accessed 07/08/18.