Grenade fishing is a bad idea and these gentlemen show us why.
Grenade fishing is a harmful way to kill or stun fish from the concussion of the blast underwater and destroys fish habitat. After the blast the fish victims come floating up to the surface.
And of course, there are plenty of ways for it to go wrong. Like this.
It's more harmful when the grenade fisherman doesn't know when to let the grenade go!