You can safely swim behind a large fish as long as you don't touch its mouth. Use them as a "shield" to clear a path through smaller fry.
If you love the gameplay loop, check out Feeding Frenzy (available on Steam/Xbox) or Hungry Shark World . They take the "Fishy" formula and add 3D graphics, power-ups, and massive maps. Pro Tips for Survival fishy-3d-free-download-pc-game-full-version
fish bigger than you, or you’ll become their dinner. You can safely swim behind a large fish
Fishy 3D is a simple but addictive "eat-em-up" game where you start as a tiny fish in a vast ocean. The rules are straightforward: fish smaller than you to grow larger. fishy-3d-free-download-pc-game-full-version