Mean to eat mostly raw fish (8)
I believe the answer is:
stingray
'fish' is the definition.
(type of fish)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for stingray that I've seen before include "swimmer" , "Marine creature with venomous tail" , "Large fish with tail spine" , "Large venomous fish -- it's angry (anag)" , "TV show" .)