When you catch a fish it would be pretty cool if you could place them in the water barrel and keep them alive. They swim around and stuff and slowly grow into trophy fish the longer they stay alive. Takes ages though so its not really viable to farm trophy fish but it would mean keeping fish alive would have a purpose if you are doing a fishing session.
Its more for fun really.
If your ship gets filled with water it will overflow and they will swim around the ship, and thrash on the deck when its dry.
You can place them back in the water barrel or eat them.
Or..grab the fish and use it as a weapon. Trophy fish deal slightly more damage as they are bigger. Fish like storm fish can even cause shock damage.
However fish have durability and end up becoming a fish bone after a few hits and giving zero damage.
Monty Python - The Fish Slapping Dance
