This is my adaptation from the Three.js Birds Demo which was featured in the famous HTML5 Music Interactive Film The Wilderness Downtown.
The original birds demo was done by Mr.Doob based on the boids simulation. You can read more about behind the scene of The Wilderness Downtown and the flocks of birds simulation from his blog here. (Thank Mr. Doob for your awesome Three.js library and the nice bird demo.)
The significant adaptations that I made to this school of fishes simulation are: the fish objects are PlaneGeometry with bitmap texture; some tweaks to the boids' speed and movement to make them more fish-like; and making the fish wiggle its tail instead of bird wings' flapping.
This fish and the bird demos are used in my side-project for my friend's HTML5 portfolio.
Now, go see the demo. The source code can be found on Github.