How And Why Do "dither" Fish Work?

[xanthedc]

In my tank I have a brute of a platy; a huge female one and she ran the tank. She kept all the neons cowering at the back. She kept the other two female platies on a short leash, where ever they were she wasn't happy with them and used to chase them. Now I read that dither fish, especially danios, were good at keeping assertive fish in check.
It's true within a few minutes of the 6 danios arriving and zooming around, speedy fast, big momma platy was reined in.
I now have a much more peaceful tank. The neons are swimming about and are even coming to the front of the tank. The other platys are not harrassed as much as they used to be. Every now and then she might have a go but not nearly as much as she did.
What I was wondering is how do dither fish work? Do they give the other fish confidence or do they just chase them out of their comfort zones as they are so speedy fast? Just curious about the psychology of fish?
If anyone has some fish philosophies then please share.

 

[Liam]

The more fearful fish see the others zapping around the tank and feel safe, they decide there are no predators around so come out more. Danios make good dither fish as they are always swimming about fearlessly.

 

[wendywc]

That's strange about your female platy. Mine have always been the sweet, going-everywhere dither fish for my tank. Glad everything has worked out for you though!