Four to five days after koi eggs are
the eggs will hatch into koi larvae and reveal their first signs of
life to onlookers. At this point,
the happy owner of these newly hatched koi can't help but feel a
well-deserved and overwhelming emotion of pride and success.
But there's still one important task left at hand - nursing the larvae to health until they can properly take
care of themselves.
Koi larvae do not have a
developed swim bladder and can not control their buoyancy in water.
They swim vertically by twisting their tails and require frequent
rests, which they get by attaching themselves to substrates immersed
in the water. Because of their inability to swim well,
the water in the tank of the larvae must be kept tranquil, i.e., they
must not be subjected to harsh water movements.
Severe agitation of the water can easily sap the larvae of their
energy, or worse, harm their fragile and sensitive bodies.
Newly hatched larvae can be easily sucked into water filters too,
which is why water filtration is not done at this point.
Although water tranquility is a
'must' for koi larvae, it must also be emphasized that there should
adequate and unimpeded aeration in their tank because they need an ample supply of oxygen
at all times. They do not have gills and have to rely on the
diffusion of oxygen through the entire surface of their body in
order to 'breathe'. As such, they are very sensitive to oxygen
depletion as well as the osmotic pressure resulting from the water
in which they live in. Because oxygen is more easily depleted
in 'dead corners', some experts recommend that a circular tank be
used for hatching koi eggs and nursing koi larvae. This circular tank must be provided
with silent-type air pumps that can continuously circulate oxygen around the
Aside from providing a
tranquil but adequate aeration to the larvae, another
challenge is feeding them. Newly hatched larvae don't have
a functioning mouth yet so they don't need to be fed. They
will get their nourishment from their yolk during their first couple
of days or so. Only when they have fully consumed their
yolk will there be a need to feed them. Koi larvae normally
begin their active quest for food on their third day.
Koi larvae must have ready
access to food. Unfortunately, d
foods can not be given to them because these are still harmful to
them. Dry foods will also pollute the water quickly,
especially in the absence of water filtration. Instead, live
and natural foods such as infusoria, daphnia (see Figure 1), and
brine shrimp (Artemia) nauplii must be provided to the larvae.
By the way, koi larvae rely heavily on vision to hunt their food so
they should be provided with a high level of illumination during
each feeding, which is done 5 times a day.
Daphnia is a recommended food for koi fry.
After 6 to 8 weeks of live
feeding, the koi fry should be ready to eat dry foods. If
everything went well up to this point, the koi fry are well on their
way to growing into healthy koi adults and the koi keeper can
Koi Breeding Considerations;
Basic Koi Breeding Method;
Dry Method of Fertilization