Kept in the refrigerator you will get a couple weeks out of them ( they turn dark when they are on their way out). Here you can catch a wide variety of fish even pike and musky from time to time. Strikemaster offers the Puck for storing or carrying them, also there are larger keepers available for longer storage of larger quantity. This definitely improves longevity. Buying them on line is also a good alternative if finding them is hard.
Nothing magical about them, but under the right conditions you may think so.
WS