Here is the full list of all 21 Pacifish achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Spin reels 50 thousand times
Defeat 50 thousand enemies
Acquire Sam's journal
Find all five shells
Find the Black Orb
Complete 50 thousand catches
Defeat all bosses
Own all tackle
Own all fishing poles
Unlock Dam and Sky fishing
Reach Fisher level 100
Use 1000 bait
Get 1000 matches
Reach fight area 100
Hatch 10 million fish
Earn 50 million pixels
Craft 20 fishing pole mods
Earn 500 million coins
Reach Market level 50
Eat 10 million fish
Reach Swimmer level 10