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