Here is the full list of all 19 KOI (CN) trophies - there are 17 bronze and 2 silver.
Total play time is 24 hours
Avoid being hit by a single spark in Level 6
Make an opened flower light up 30 times
Complete the upstream part of Level 7 in over 3 minutes
Remain undiscovered by the Black Fish in Levels 2 and 5
Unlock all the Skins
Bump into an obstacle 200 times
Dodge 20 attacks of the Black Fish
Suffer 20 attacks by the Black Fish
Complete every level
Collect all the Puzzle Pieces in the game
Collect all the Stars in the game
Open all the flowers in the game
Reach the frontier of the 3rd part of Level 7
Don't miss a single encounter with Old Toad
Complete the upstream part of Level 7 in under 3 minutes
Get hit by sparks 5 times
Lead more than 50 small fish in total
Total distance traveled over 8000 meters