What Are Infusoria?
Infusoria is a catchall term for
microscopic organisms that live in any
body of freshwater, including ponds,
streams, and even water found in flower
vases and flowerpot overflows for that
matter. They are also present in aquariums,
but not in numbers that will support
newborn fry, though hundreds can exist in
a single drop of water.
You can think of infusoria as freshwater
plankton. They may be made up of
paramecia, algae species, euglena, and
other protozoans, as well as some species
of multicellular animals such as rotifers.
The most nutritious of the lot are the free-swimming nonphotosynthetic paramecia
and the rotifers. They will give any
newborn fry a very nutritious meal and
therefore a good, healthy start in life.
The important thing is to have a ready
supply available. Fortunately, growing
infusoria is not difficult at all because they
are ubiquitous and the process costs the
aquarist little to nothing.
A Good Recipe
As with any recipe, you have to start
with the right ingredients. First, you need
an adequate culture of infusoria to get
started. A pond might be a good source,
but unfortunately, it is a good source for a
lot of other things, too, such as damsel and
dragonfly larvae, water boatmen, diving
beetles, hydra, and planarian worms that
may prey on not only your fry but also your
You can use tap water instead, but
let it age for a while since it is infused
with chemicals to kill many of the very
microorganisms that you are trying
to grow. Another possible source for an
infusoria culture is a vase of cut flowers.
You must be careful here, however, as some
commercially sold flowers are sprayed
with chemicals that may compromise your
culture. Commercial sources are another
option, but perhaps the best source is right
at your fingertips. Remember that infusoria
exist in small amounts in aquariums, so
there is absolutely no reason not to start
your culture with the same water in which
you are keeping your fish. If you have
plants in your aquarium, the water is even
better as a starter culture, as it will naturally
contain more microorganisms.
The easiest way is to just draw water
directly from your aquarium, and some
aquarists use the dirtier water you can
get by squeezing a filter sponge. If you go
the tank-water route, be sure that your
aquarium has not been treated with any
chemicals for a while since that can affect
the growth of an infusoria culture.
In addition to the starter culture, you
will need some organic material to grow
the culture further in order to produce
the amount that will feed your fry. Many
early aquaria textbooks suggest placing
boiled hay or grass in the water. There
are other options. If you have either apple
snails or Colombian ramshorn snails in
your aquarium, their droppings, composed
primarily of partially digested plant
material, make excellent starter media.
Brewer’s yeast tablets, ground-up lettuce
leaves, and cucumber skins also work as
The easiest and neatest source of organic
material might be rabbit food tablets. Just
one per container is usually sufficient. You
can also try your own organic recipes, as
any organics will do; however, be careful
not to overload or you may end up with a
smelly bacterial soup instead of a healthy
86 www.tfhmagazine.com Jul/Aug 2017
This tiny Tanichthys micagemmae fry
found on an aquarium’s front glass is
too small for conventional fry foods.
Paramecia photographed at high magnification.