The Blue fish

Found in the river running through the island. They mate in salt water, but travel in fresh water too. The blue-coloured fish, affectionately known as the bluefish, has some unknown bonus properties. For one, they appear to be utterly necessary to the production of wine. This fish has been thought extinct for a long time, and with it disappeared the islands' wine trade. However, The Party happened upon one of these "extinct" fishies. Unfortunately, there's no proof, 'cause they ate it.