I loved this method for cooking fillets of fish https://food52.com/recipes...
Could it work on a whole fish (pike perch)?
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HalfPint is a trusted home cook.
I don't see why it can't. It might take a little longer with a whole fish.
June is a trusted source on General Cooking.
It should work fine. Be sure to use a thermometer to ensure you don't overcook the fish. (which is just as bad as undercooking it, imho).