Create a new multiplayer gameExtension: Gathering Storm
Start era: Information Era
No City States
No Disasters
Game speed: Online
Map: True Starting Locations
Untick all victory conditions
No barbarians
Leave the rest at default settings.
Select John Curtain as your first leader. You can leave the second leader random - controlled by AI or by you, it does not matter. Select Settler difficulty for both players.
PlaythroughAs John Curtain, delete all your units but one settler (keep the northernmost one if possible, it'll save you some travel).
Don't build a city yet. You can choose a Pantheon if you like (it does not matter).
Travel north by following the east coast, until you reach the Great Reef barrier wonder (might take you 3-4 turns). Found your capital once you are within 1-2 tiles of the wonder - so that at least one tile of the wonder is next to your city center.
Delete all units again, except your builder. Send your builder on a water tile next to the Great Reef Barrier (there should be at least 1 within your city's bounds). Put your builder to sleep once it reaches its destination.
Now, set Liang as governor in your city. Unlock her Fishery ability (first row on the right).
Skip turns until Liang is established (shift + enter repeatedly).
Once Liang is established, select your builder, and choose "Fishery". The achievement should pop.