You may have seen this under the (incorrect) name Rock Salmon in your local chippie.
Also known as Huss or Rock Eel, Dogfish range from 450g to 1.5kg and look similar to a small baby shark (they are related).
The skin is very tough, but the pinkish flesh is usually sold skinned and trimmed leaving just the central cartilaginous backbone.
These can be cut into chunks and used like Monkfish or battered and deep-fried.
It is also good in curries and other strong flavoured dishes.