AMAZONAS
Incubation and rearing
When the spawning spree has ended and the animals lose
their courtship colors after several hours, the spawning
trap should be removed immediately for maximum yield.
But for smaller yields, you can remove it one or two days
later. Carefully rinsing the gravel over a floating breeding
box or a breeding ring (see AMAZONAS website) placed
directly in the breeding tank has worked well for me. In
the case of the adherent eggs of C. lutrensis, the entire
spawning trap is transferred into a suitable rearing tank.
Depending on how much time has passed since spawn-
ing, eggs or already hatched larvae can be harvested that
way. Depending on the temperature, the fry of both
species hatch in about two days. The eggs, or the 3–4-mm
glassy larvae, are incubated in the breeding container or a
suitable rearing tank.
At first the larvae rest passively on the bottom, but
after a day or two they react to any vibration or sudden
light by fleeing in panic. Therefore, the container should
be darkened at least until they swim free. Alternatively,
you can provide some leaves or Java Moss for shelter.
Another two or three days later the larvae use up their
relatively small yolk sacs, swim free, and begin to take
food. Paramecium (ciliates) and other infusoria work as
first feed, although suit-
able fry food for fish larvae
and even finely ground dry
food is also appropriate.
Just a few days later the
larvae begin to take freshly
hatched Artemia nauplii,
and from then on rear-
ing is routine. Good tank
hygiene and clean water
are important. Feeding
them two to three times
a day will allow them
to grow at a good rate,
increasing their size by 3–4
mm per week. Pushing
faster growth could be called “steam breeding,” which can
impact condition and color later.
At about four weeks, the young fishes are about
0.75 inch (20 mm) long and their growth slows down
significantly. Animals of this size will still take Artemia,
but they will also start to eat small Daphnia, Cyclops, and
fine dry food. At about four months, Rainbow Shiners
reach a size of about 1.5 to 2 inches (4–5 cm), and they
become sexually mature at about six months. The same
applies to C. lutrensis. So if you put in the effort, you can
easily raise two generations per year. If you have several
hundred animals, they can be reared in outdoor pools
(e.g., large rainwater collecting tubs or ponds) or kept
in a pond (Andreas Müller, pers. comm.). Luckily, both
of these shiners are very adaptable in the aquarium and
outdoors and easy to maintain for the hobby.Invasive species alert!
Finally, a very important warning: Most North American
fishes from temperate regions, including these shin-
ers, can easily survive European winters, propagate, and
spread. For this reason, they have to be classified as po-
tential invasive species that could displace or affect native
species. Therefore, if you want to keep such animals you
must ensure that no animals or
their spawn enter natural bod-
ies of water. This applies, in
particular, to outside pond
culture. If you cannot guar-
antee that you can handle
them safely, you should not
keep them.
Editor’s note: This
warning also applies in the
United States. These species
should never be released
into natural water bod-
ies, even in their native
range. Feral animals could
negatively affect the wildIn a dark aquarium with the filter return run along the front, Notropis chrosomus come
into their own. The fish are always at the front of the tank, swimming against the current.
A pair of the blue form of
the Rainbow Shiner over
the spawning substrate.