Never use live shrimp but for shiners in the summer we always change the water out occasionally and place some frozen water bottles in the buckets. Don't try and put too much bait in one bucket/livewell or they will die Warm water can hold much less oxygen than cold water so keep your water cool and your bait will be happy. This is why you see shad on top of water in middle of summer because the water is low on oxygen and they are gulping air. Was on the river last year and two people were in a boat and complaining about their shiners all being dead. Said they got some bad shiners. Had about 100 in a one gallon bucket sitting in the sun in July. Told hen hey need to keep changing the water out and they said they didn't bring any extra water
Be careful using ice also as it can kill your bait with the chlorine it has in it you can put ice in a ziplock bag and that will cool your water
one other tip is if you get minnows or shiners the day before. Place them in a bag with oxygen and put them in your refrigerator overnight They will all be alive the next morning
Or you can stick a yeti sticker on your bait well and it will keep it cold forever but check it occasionally for freezing