What cultural preparation practice is used in traditions like Polish Christmas Eve dinners to cleanse the fish of lingering off-flavors?

Answer

Keeping the live fish in clean water for several days

In Polish tradition, a 'purging' period where the live fish is kept in clean water for several days is often employed to cleanse its system of any lingering off-flavors before cooking.

What cultural preparation practice is used in traditions like Polish Christmas Eve dinners to cleanse the fish of lingering off-flavors?
dietanimalfishcrucian carp