Do you need to put water in the bag with fish prior freezing it If so why?

No, you don't need to put water in the bag with fish before freezing it. In fact, it's generally recommended to not add water to the bag with fish when freezing it. Adding water can lead to the formation of ice crystals, which can damage the fish's cells and tissues, resulting in a loss of quality and flavor.

For best results when freezing fish, it is best to freeze the fish dry, without any added water. This helps to maintain the fish's texture and flavor by preventing the formation of large ice crystals. To prevent the fish from sticking together, you can place a layer of plastic wrap or parchment paper between each layer of fish before placing them in the freezer.