If you have fish in it & are going to move them within a reasonable time . IMO make a slush by adding saltwater .
Also IMO if you going to hold them >>>> 2 days .... pack in ice .......I always have enough ice to leave the drain open . I don,t want them in fresh cold water .
If its just ice ..I always leave it open .
Right now my cooler is filled to the brim with large ice chips //////////super to dig a cup into in this hot weather
