Dither fish are typically non-skittish, schooling fish that are
introduced to an aquarium to
encourage more shy species to
hiding, to help diffuse aggression,
or in some cases, to encourage reluctant
breeders to spawn. A few good examples of
commonly used dither fish include zebra
and giant danios, cardinal and neon tetras,
harlequin rasboras, and tiger and rosy barbs.
The presence of bold dither fish essentially
communicates that everything is normal and
natural and that danger isn’t necessarily
lurking nearby in the form of a larger predator.
(Or, perhaps, the shy fish simply thinks to
itself, “Well, if there is a predator nearby,
these hyperactive fools will probably get it
before me!”)
To get a sense of why this works, think how
you would feel when walking down a city
street where no one else seemed to be going,
versus walking on that same street with plenty
of other people around you going about their
business. In the first scenario, you’d probably
feel a bit anxious or intimidated, wondering
why others seemed to be avoiding the street,
while in the second scenario, you’d probably
be more at ease.
A
Dr. Jurgen Schmidt
Zebra danios Danio rerio are commonly used as dither fish, with their activity in open water helping
to embolden more reclusive fish to come out of hiding.
A good choice in a dither fish species is
one that tends to gather in tight schools,
is fast enough to evade any aggressive
action on the part of the fishes you’re
trying to coax out of hiding, and is large
enough that it won’t be swallowed by its
timid tankmates should they start to feel
their oats.
