Infusoria are the perfect food for young fish fry.
ou wake up one morning, switch on the aquarium light, and
there they are—you barely see them—tiny, almost transparent fish.
One of your tetras or barbs has laid eggs that have now hatched. How
do you feed these nearly invisible fish? This is a common problem
for aquarists who keep egglaying fish, as the fry are so small that
conventional foods are not appropriate. There is an answer, though,
and it is closer at hand than you might think.
Whether you are raising anabantids, tetras, danios, barbs, or any of
the many other egg-laying species, you have several days to prepare,
as the fry will be nourished by the still-present yolk sac. After the
yolk sac is absorbed, however, the fry will be famished and will need
nourishment if they are to survive, so you have to be ready.
First, you should move the fry from the main tank to a fry nursery
tank; otherwise, their parents or older siblings may make a meal of
the newborns. Many articles are available that explain how to set up
such a tank. Note, though, that there are exceptions to moving the
fry. Most cichlids, for example, make great parents, and removing
their young too soon may actually prove harmful.
Now, how do you prepare to feed your fry? Commercial fish food
is not really the answer, because even some of the powders are too
large for fry, at least in the initial stages of their lives. But readily
available is something hidden right inside your aquarium that is
often identified in fishkeeping texts, especially older publications, as
infusoria. Infusoria are the perfect food for young fish fry.
This micrograph illustrates the wide variety of
microorganisms that make up freshwater infusoria.
INVISIBLE FOOD FOR TINY FRY