I've never fished with a grenade but when I was a youngster, they were blasting out the Livingstone channel in the lower Detroit River for the St Lawrence Seaway.
I was fishing with my uncle and when the siren sounded we would run the boat a few hundred yards downstream. when the blast went off I was charged with operating the landing net as my uncle maneuvered the boat near the stunned fish.
Some days fishing was pretty good