[8:17:55 PM] Jordan Coles: I'd like them to improve fishing, then I'd make a fishing lodge and trade through that
[8:25:19 PM] Jordan Coles: If they added fishing nets/lobster pots, fishing trawler ships, and added stardew valley mechanics to the quality rod then it would be in a really cool spot. Give "big catches" the same values as some of the higher tier cheeses and then apply a fishing skill or tie that to charisma or con + str
[8:26:06 PM] Jordan Coles: If the fish had a value then I could definitely see them being a specific industry you could focus on as a trader
[8:26:32 PM] Jordan Coles: I'd also like to see fish tanks, fish weights/sizes upon catching them and stuffed wall trophies
Fishing trawlers

A boat with a net and a storage box. When a person is boating on top of a fish node, fish are slowly collected and placed into the boat's storage container.
The boat would only harvest when someone is in the driver's seat and it is unable to pull in "big catches"
Stardew Valley fishing minigame
https://youtu.be/KSJo-AaV0hY?t=44s
It would be cool to make more specialized industries, where a person could focus on one thing and make a living by trading things from that industry alone
I think the main thing would be to expand on how you fish, and the fish being caught. Fishing can be a viable trade industry if the "big catches" are on par with some of the higher-end cheeses in terms of FEPs.
I'd also love it if the fish being caught would have a weight attached to it.
Another fun thing that I've considered is if you catch a fish and then drop it back into the water you are "releasing it" so when it is caught again by another player, its size will have increased significantly (since all objects are saved when dropped now). Fish size might determine things like extra stat boosts on the cuts, the amount of food that is crafted in the end recipe (ex. 2 pieces instead of 1), the amount of pieces you get when you butcher the fish, and the size of your E-peen.