There might be other ways and with differant fish, tried it with bass and trout, but yellow perch works best for me.
Fillet and skin perch and cut into shrimp size chunks.
Boil pot of water, I add spices such as OLD BAY crab spice to the boiling water.
Using a metal basket or strainer, put fish into boiling water.
Shouldn't take more than a couple of minutes, The fish pieces will turn white and curl up.
Remove basket from boiling water and run under ICE COLD water.
This gives it a shrimp like look and feel.
Now whip up some cocktail sauce with extra horseradish and open a bottle of adult beverage and enjoy.