This is a work-in-progress project, ported to OpenFrameworks from Processing, you can see the original sketch here http://www.nardove.com/koifishpond/
Every fish is build from 5 different parts, head, body and 3 tails. Tails and body extend the same class Flagellum, this class is based on the work by the same name http://levitated.net/daily/levFlagellum.html
Next steps are: some more tweaking, try other fish textures, implement some multitouch feedback, and more important implement shaders effects, but I need to learn it first.
It runs at 60fps with 200+ objects easy, but I need a bigger screen ;-)