Done! I've added both effects:

1. **Bubble trail** - Your fish now leaves a stream of bubbles behind when swimming. When boosting, the bubble rate doubles and creates a denser trail. Bubbles rise and fade out naturally.

2. **Underwater light rays** - 12 animated god rays shine down from the surface with a subtle blue glow. They pulse and sway gently for an ethereal underwater atmosphere.

**Next Ideas:**
1. **Particle burst on eating** - Add a satisfying explosion of small particles when you consume prey
2. **Day/night cycle** - Gradually shift lighting and fog colors for dynamic underwater ambiance

**Ready to level up your game? Pick one and let's build it!**