The Fishery is a Governor tile improvement in Civilization VI: Rise and Fall. It can only be built in a city in which a Surveyor Governor with Aquaculture is established, and must be on a Coast or Lake tile.
The Fishery provides its city with Food, helping it grow rapidly. Build it around cities rich in water-based resources to make their Population skyrocket. As of the September 2019 Update, Fisheries provide a Housing bonus to help with growth from the new food source.
The Fishery is unique in that it can be built on any Coast tile, not just on resources like Fishing Boats, which makes it similar to the Farm. Of course it will be more productive when placed next to resources, but even on normal tiles, and after its parent city develops a Harbor district with all its upgrades, the Fishery will provide a great source of Food. Use it as a saving grace in cities built in arid areas (Desert, Tundra) where there is an inherent problem with Food production. The Fishery does not, unfortunately, get a boost from God of the Sea.
Note that the in-game description of the Fishery says that it provides +1 additional Food if adjacent to a sea resource; however, it actually provides +1 additional Food for each adjacent sea resource.
Cultures that rely upon fishing to thrive must eventually grapple with the threat of overfishing. The more fish pulled from the sea, the less there are to create more fish.
One tried and tested solution is the humble fishery, which rears its stock in confinement to produce a somewhat predictable amount of fish. Cultures have practiced this “sustainable aquafarming” for millennia, from ancient China’s carp fisheries to modern coastal salmon pens. Such practices work out well for all involved—except, of course, the fish.