If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
This game has ten levels altogether. To enter in next level you should eat all fishes, and 1 fish carries 10 points. At each level, an enemy fish attacks the Piranha, and as the level increases the enemy fishes increases. Piranha has three lives to complete 10 levels.
Use arrow keys to eat the fish foods.