Redspotted tonguefish. Photo by Jeff Corbett
Sand tonguefish. Photo by Guido Zsilavecz.
Lemon sole. Photo by Guido Zsilavecz.
Tonguefishes differ from the more commonly seen soles by having their eyes on the left side of the fish, whereas soles have them on their right side. This is not always visually apparent, but all you need to figure out is where the mouth is - on a fish with the head pointing left the mouth is at the bottom for a tonguefish, on top for a sole. Another distinction is that in tonguefishes the dorsal, caudal and anal fins are continuous, forming a pointy tail - soles have a distinct bushy tail.
In Cape Town waters there are two tonguefishes, the other one being the sand tonguefish, C. capensis, which has a cream base overlaid by a blotchy light brown pattern. The redspotted tonguefish differs especially in having red spots on the fringing fins, as clearly shown in Jeff's photo.
See "Coastal fishes of the Cape Peninsula and False Bay", available from SURG, for more details.
Coastal fishes of the Cape Peninsula and False Bay, a divers' identification guide, G Zsilavecz, 2005.
Smiths' Sea Fishes, MM Smith and PC Heemstra, 1986.
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.