Is grouper kosher?
The signs of a kosher fish are scales and fins. If the fish does
not have either of these, then it is not a kosher fish. If it does,
it is a kosher fish and one may eat it provided, of course, that it
was prepared with kosher ingredients.
According to "kashrut.com" (see link in related link section),
the Grouper is indeed a kosher fish.