Fish preservation

I suggest a fish tank aboard all ships that can preserve fish. To elaborate, all fish would slowly rot if just left in a food barrel, so before cooking it you can drop them in the tank and also just watch them swim around. You would be able to take them out but not put them back in after cooking them. This would add something fun to watch when you're bored and also add a bit more urgency to fishkeeping. The tank might also have a leak in it that requires you to dump water in it occasionally if you want to keep fish alive and not rotting.