I beat the hardest Feeding Frenzy 2 level in  

Thumbnail unrelated, I just thought it would be funny
This is the most asinine level in the series and I have two other Feeding Frenzy 2 speedrunners to vouch for me.
The trick here is to play slowly and patiently; enemy fish would generally only move in one direction… unless they bumped into a puffer, ran into an ink cloud or ate a poison minnow which are the ONLY THING YOU COULD EAT TOO.