he Silver Arowana (Osteoglossum bicirrhosum) is a long and
beautiful fish known for its voracious appetite and constant surface
skimming, looking for things to fit into its mouth. It is native to
waterways of the Amazon River and other areas in South America. It is a
very popular fish for intermediate to expert aquarists as it swims
fairly gracefully and with purpose and has a nice and powerful jaw.
Aquarists like to watch it feed, especially live foods such as
earthworms and other insects. A true carnivore, the silver arowana can
be aggressive, especially toward smaller fish in the tank, so if you are
going to keep an arowana with other fish, choose tankmates wisely. Fish
that inhabit the middle and lower portion of the aquarium's water
column are preferable. The silver arowana's domain is near the surface,
where it stays most of the time. The silver arowana is a visual hunter,
and it has been observed in the wild jumping out of the water to snatch a
hapless bug from an overhanging tree branch.
The silver arowana is not a beginner fish, but is more suitable for
intermediate to advanced aquarists. It requires a large aquarium with
strong filtration and a diet of primarily live foods such as feeder
fish, earthworms and other insects. It will also eat floating
foodsticks.
With proper care, the silver arowana is a very hardy fish. It can have
issues such as gill curl, which is often due to bad water quality and
limited space to move about; white spot (ich), cloudy eyes, and coned
scales are the other arowana ailments. Common cures can remedy these
conditions.
The silver arowana can grow to more than 3 feet in length. It has an
elongated body, almost knifelike in look, with a compact and
wedge-shaped head. It has a wide, underhang jaw that opens like a
trapdoor whenever it feeds. It has large scales and two barbels hanging
from the tip of its jaw, hence the scientific name bicirrhosum, which
means "two barbels." The barbels are sensory organs, able to detect
movement on the water's surface.
The fish is found in the Amazon Basin, with related species such as the
Asian arowana found in Asia, and an Australian species. It resides
primarily in slow-moving rivers and waters that flow into swamps and
wetlands.
The silver arowana is best kept in large aquariums with tankmates that
are just as large or too big to fit into its mouth. The silver arowana
can share space with larger fish that inhabit the lower strata of the
aquarium, such as clown knifefish, large plecostomus, oscars and other
large cichlids. The silver arowana can also live alone or in groups of
three. The Australian arowana is best kept alone in its own aquarium.
Due to its physiology and natural habits, a long tank is desired over a
tall one, with recommendations of the aquarium measurements equal to
three times the length of the arowana. A minimum tank size of 72 by 30
by 24 inches is ideal. Two hundred gallons is the generally accepted
minimum capacity. Ideal water conditions are pH of 6.0 to 7.5 and a
water temperature range of 75-83 degrees Farenheit.
The silver arowana requires a long, rectangular aquarium with a lot of
surface area to patrol as it spends most of its time swimming back and
forth on the surface looking for food. A lid is also required as the
arowana is a very accomplished jumper. Because it eats so much, the
silver arowana produces a lot of waste material, so frequent water
changes are a must. Bi-weekly water changes of 20 to 25 percent are
ideal. Pay special attention to water conditions and test for ammonia,
nitrate and nitrites regularly.
Most silver arowana in captivity are bred on fish farms. The fish is a
mouthbrooder, with the male doing the babysitting for three weeks until
the fry reach a size of around 3-4 centimeters, where they can then hunt
on their own, returning to the male only when danger arises. At
approximately five weeks, they leave the male for good.