Spareful Hand
Stores certain large-sized fish as swimbait for later use.
Swimbait may be selected for use as bait so long as you remain at your present fishing spot.
Swimbait may be used even after actions that cancel mooching opportunity.
Cannot be executed while under the effect of Surface Slap or Identical Cast.— In-game description
Spareful Hand is an action unlocked at level 91. It is available for Fisher.
Related actions
Notes
Spareful Hand lets a fisher save a fish that would be moochable for future use as "swimbait".
A fish's eligibility for saving is checked only when the fish is caught. Therefore, fish caught while under the effect of 
Makeshift Bait are still eligible even if Makeshift Bait's effect ends after the catch. Large-sized fish are always eligible for saving.
Swimbait can be selected from the 
Bait menu like a regular bait, and then cast out using 
Cast. Actions that would normally cancel mooching opportunity are allowed to be used on swimbait.
If the player moves or 
Quits the fishing stance, all unused swimbait is lost.
Guides
Brief video guide by Fruity Snacks: Putting fish in your pockets is helpful.
History
Patch 7.0 (2024-07-02): Added.