Here is the full list of all 40 Little Crab Fisher achievements.
Catch 10 Mythical Crabs
Collect 1 Of Each Mythical Crab
Collect 1 Crate
Collect 5 Crates
Collect 25 Crates
Collect 50 Crates
Collect 100 Crates
Name Your Boat
Collect All Relic Fragments
Defeat Clatastrax
Manually Harvest 10,000 Crabs
Manually Harvest 50,000 Crabs
Manually Harvest 100,000 Crabs
Prestige 1 Time
Prestige 2 Times
Prestige 3 Times
Prestige 4 Times
Purchase All Boat Themes
Purchase All Boat Items
Purchase All Boat Flags
Purchase All Premium Cosmetics
Open 50 Pirate Chests
Purchase All Shop Upgrades
Catch 1,000 Crabs
Catch 10,000 Crabs
Catch 100,000 Crabs
Catch 1,000,000 Crabs
Catch 25 Green Crabs
Catch 100 Green Crabs
Catch 500 Green Crabs
Catch 1,000 Green Crabs
Catch 5,000 Green Crabs
Catch 10 Blue Crabs
Catch 25 Blue Crabs
Catch 100 Blue Crabs
Catch 250 Blue Crabs
Catch 500 Blue Crabs
Catch 1 Mythical Crab
Catch 5 Mythical Crabs
Catch 100 Crabs