If it is any good to any crappity smack I used to keep mine in cat litter trays with just enough water to cover the bait. Used to change the water every two or three days when they were also riddled.
If you find the bait still dies it is all to do with the water you are using. Can't remember which way round it is but people live in hard water and soft water areas. To combat this I used to boil some water then just let it go cold again; it was OK then. Like I said I ain't no crappity smack Scintist (can't even spell the crappity smack word) but this worked every time if you lived in a 'wrong' water area.
Another way of keeping bloodworm is to keep it in plain and simple in wet spagnum moss. I don't know whether they still do but the Belgians used to keep it for ages in this fashion, they used to take as much as they needed to the bank in little tins and pick it directly off the moss. This worked very well but you still may have to get the water right before you wet the moss, - it is much cleaner and less time consuming this way as well.
I just can't remember if it was soft or hard water that destroyed the bait quickly. Hope this helps.
You can also keep it in dry peat for quite a long time but it does shrink and becomes less active after a while.
As for worms as long as they are fresh they should easily keep for at least two months in the bottom of the fridge. Keep turning the bag over and add a bit of food, egg shells, spud peelings occasionally and they will live longer. If they die after a couple of weeks in the fridge, they are just too cold (unlikely) or you have been sold worms that are a lot older than you think they are, (very likely).
If you are sold squatts that are mushy wet they will not last long either. They look right and are OK to fish with but as soon as they start to dry they die. This was always a quick fix to extend the selling ability of them.
All my opinion of course but I did look after bait in a shop for over ten years.
Casters that are dark can be made to look bright again with icing sugar or that liquid they stick in wine making. They also sink but will go green/brown/grey in a short time. If you have had any of these you have also been 'had.' unless that is what you want.
DeBAIT over
