Here is the full list of all 21 Tasty Blue achievements.
Beat the game on any difficulty in two player mode
Eat 100,000 objects
Earn all stars on hard difficulty (or harder)
Earn all stars on deadly difficulty
Earn all stars on normal difficulty (or harder)
Earn all stars on easy difficulty (or harder)
Eat 50,000 objects
Complete the main game on normal difficulty (or harder)
Complete the main game on hard (or harder)
Complete the main game on deadly difficulty
Complete the main game on easy (or harder)
Earn all stars on very easy difficulty (or harder)
Eat 25,000 objects
Complete all bonus levels on any difficulty
Complete all shark levels on any difficulty
Complete the main game on very easy (or harder)
Complete all dolphin levels on any difficulty
Eat 10,000 objects
Eat 5,000 objects
Complete all goldfish levels on any difficulty
Eat 200,000 objects