Dithers are absolutely essential to keeping large, aggressive fish, with less aggressive tank mates. Dithers are fast and agile fish, that swim together in packs, which distracts the aggressor, but they look too large and are too fast to catch.
A link to my dither video: http://www.youtube.com/watch?v=3IPMLU85YcA
A link to my dither video: http://www.youtube.com/watch?v=3IPMLU85YcA