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