Fish Hatchery is a structure you can add to your backyard in Skyrim: Hearthfire
How to add fish to a fish hatchery in Skyrim Hearthfire
The Fish Hatchery can only be added to the Windstad Manor in Hjaalmarch. It cannot be added to other houses.
You should have the option to build the Fish Hatchery once you have added a door to your house.
Additions
Clam Meat
Cyrodilic Spadetail
River Betty
Salmon Roe
Silverside Perch
