If you are about to install a game update or mod the game, create a backup immediately. Updates can sometimes wipe progress.
Alternatively, you can use the feature by right-clicking the game in your library, selecting Properties > Installed Files > Backup game files , though this often only backs up the game installation rather than dynamic save data. Editing Your Save File feed and grow fish save file
Disclaimer: This removes challenge. Use only for fun. If you are about to install a game
Because the game is in active development, save files can occasionally become corrupted during updates. It is highly recommended to your files: feed and grow fish save file