Open the save file directory using the Run command method listed above. Select all files inside the folder. Right-click and select Copy (or press Ctrl + C ).
If you want to try modifying your save data, always use a proper text editor like rather than standard Windows Notepad, which can strip formatting and break the file entirely. Crucial: Back up your save file before making any changes.
If the game tells you your save is corrupted, the FishSave.dat file has likely been damaged (often by crashing during a save). Unfortunately, there is no built-in way to repair it. You will have to delete the file and start fresh—unless you have a backup.
Sometimes Steam tries to download an older save file from the cloud, overwriting your newer local progress.