
You could always try throwing them to the dogs for them to catch - they tend to gulp them down then. My newest rescue dog wasn't sure what to do with them when they were put in his bowl but throwing them to him a few times worked and now he eats them straight from his bowl.
My GR took his first raw fish up the garden and rolled on it before realising he could eat it. The bringing it back up again is not uncommon but mine just view it as a second meal and devour it again.
If you are going to warm them up make sure you don't cook them for too long as cooked fish bones are very sharp.