I used to do this sometimes with my salt water fish. Couldn’t taste the difference, just made cleaning them a little less nasty. Ice with water and salt to make a slurry is a great way to quickly and humanely dispatch a crappie. A few seconds in the slurry and they are done. Easier to clean because they get real firm. I can’t clean fish if they are flopping about. Makes me think they are feeling the knife.