Hi Judy,

to get rid of parasites in raw fish, maybe one way is to keep the fish
at room temperature in an airtight box for app. 3 or 4 days. Of course
it will smell awful afterwards.
If there are parasites, it is most likely, that they are developing and
growing then, so you can see them.
To make the fish eatable, you would have to dry it then. This is very
similar to my "Mackerel Wienerwald" recipe.

You would have dried fish then - not so nice as raw one, but better
than nothing.

Best fishy regards,

Stefan