'Dither' fish...

[TheRealAndyCook]

Dither fish are schooling, mid-water swimming fish that are used to bring hiding fishes out into the open. Smart fish like cichlids use the presence of smaller fish around them to judge the degree of danger around them. The idea is “surely if hundreds of those little tetras are swimming around above me, there must not be any imminent danger”. !

quote from http://mikejacobs.50megs.com/DitherFish.html

 

[Dark Jester]

Actually a wiki page on it: http://en.wikipedia.org/wiki/Dither_fish

The term dither fish refers to an arbitrary group of aquarium fish used by cichlid keeping aquarists to reduce innate timidity in some species of cichlids (Barlow, 1967). The technique relies on the ability of cichlids in an aquarium to use the behaviour of other fish species as a measure of environmental security (Loiselle, 1979). Good dither fish are typically schooling species such as Danio spp., barbs and some tetra species.

That's about all there is. Looks like you're pretty close to the mark though.

Here's another page: http://aqualandpetsplus.com/Cichlid,%20Dither%20Fish.htm

That one looks like it incorporates both of our interpretations.

 

[TheRealAndyCook]

donno why i didn't just go to wiki, too lazy, its 3 in the morning here.