They need to be alive when you use them whether you cut them or not. Otherwise they will get mushy and lose their color and scales. I would not recommend adding crushed ice in a large amount to live minnows either. It will shock them and they'll swim right into the ice laying on top and die. It's best to use a chunk of ice out frozen bottles. I prefer using a 120 quart cooler with a 12 volt aerator with dual aeration discs. I can keep 18 scoops overnight with no problems. I'll maybe have a 1/2 scoop dead in the morning. I also use a water additive to reduce waste in the water.