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Others
/ Osteoglossidae / Arowana
Arowana, Arawana
Osteoglossum bicirrhosum | Pictures
Synonyms:
Isochnosoma
bicirrhosum, Osteoglossum vandelli
Physical description: An elongated, slender fish with lateral compression.
The scales are large and the head is
covered with bony plates. The long anal and dorsal fins extend from the midsection of the body and run to the tail.
The
pelvic fin is a long, slender, sharp ray, while the pectoral fin is also very slender.
These fins are white to silver in color,
but may darken with age.
The mouth is hinge-like and
can be opened widely. Two barbels, which range in color from black to blue to green to
red, are located on the lower jaw.
The body color ranges depending on the sex, age, and habitat of the
individual. Usually the Arowana is white with a silvery iridescence, but is often pink with a rainbow iridescence.
The
pinkish fish are often referred to as the "Rainbow" or "Salmon" Arowana.
The Arowana has two large black spots
that fade with age.
The first is located in front of the gill cover and can only be seen on young individuals.
The
second is located behind the gill cover and is dark black with a copper colored mark located next to it.
The
eyes are large and dark.
Size/Length: Specimen measuring 60" (152 cm) have been caught by fishermen in the Amazon Basin,
although the Arowana rarely exceeds 44" (110 cm) in captivity.
Similar species: Black Arowana (
Osteoglossum ferreirai), Asian Arowana (
Scleropages formosus
), Silver Barramundi (
Scleropages jardini)
Habitat: South America; the flood plains of the Amazon River and its tributaries.
S: Top
Aquarium: Young fish (under 6") should not be kept in tank measuring less than 36" (91 cm)
or 35 gallons (132 L).
Fish measuring up to 15" (38 cm) can tolerate a 48" (122 cm) or 55-70 gallon (209-266 L)
tank.
Eventually a considerably larger tank will be needed.
The tank should be well-covered for
Arawanas are fine jumpers.
Use a dimly lit tank that is arranged in dark colors and has a cover of floating plants.
The
tank can be well planted with sturdy plants.
An efficient filter is required that can remove large amounts of waste,
but not create too much surface disturbance.
Water chemistry: pH 6-7 (6.7), 2-15 dH (8), 75-86°F (24-30°C)
Social behavior: The Arowana is a large predator that will consume smaller tank mates.
This species is aggressive towards similar
species and should be singly instead of in pairs or groups.
Only combine the Arowana with large, robust species
of lower swimming levels.
Suggested companions:
Astronotus, Anostomus
, Cichlasomines, Loricarids,
Colossoma, Leporinus, Mylossoma, Pseudoplatystoma, Serrasalmus, Sorubim
FOOD: Live; fish, spiders, large flying insects,
Tubifex; may accept pellets and flakes
Sexual differences: Males have a longer anal fin while females are usually fatter when mature.
Breeding techniques: Breeding has only been accomplished a few times in an aquarium because fish become too
large.
On most occasions, spawning has occured in a tank exceeding 1000 gallons (3780 L).
The eggs are 0.5" (1.3 cm) in diameter.
The
male mouthbroods the eggs for seven to nine weeks.
The fry, measuring 3 or 4" (8-10 cm), leave his mouth after their
egg sacs are gone.
Goulding documented spawning in nature.
As flood waters rise, the cheek spot
of male Arawanas, turns bright pink.
Females are attracted to males with bright pink cheek spots, as this
indicates that sperm is ripe.
The female produces 150 to 200 eggs, which after fertilization, are taken into the protection
of his mouth.
The young hatch and remain in the mouth of the father.
The yolk-sac is used up in 2 or 3 weeks,
after which, the male lets them out to feed on microorganisms such as algae, tiny crustaceans, and insects. When
danger approaches, the male's chin barbells are used to coax the young back into the safety of his mouth.
After
4 to 6 weeks, the young are abandoned to fend for themselves.
Breeding potential: 10.
Not feasible in captivity.
Remarks:
These fish are only suitable as a juvenile for most private aquariums.
After they outgrow their tank, it is
often hard to sell them and it may be best to donate them to the local public aquarium.
They grow very fast, often more than
12" (30 cm) in their first year.
Avoid purchasing a fish with an egg sac for the fish is very delicate at that time.
When
frightened, these fish are likely to swim frantically around the tank, throwing themselves against the tank cover
and the tank sides.
Often, self inflicted injuries result.
The Arowana is an excellent jumper, capable of
leaping six vertical feet from the water.
During the flood season, the Arowana has been known to use this ability
to snatch young monkeys and sloths that are drinking.
Unfortunately, most wild-caught juveniles are caught in a very brutal manner.
Fishermen
can recognize male Arowana with young in their mouth by their colored cheek patches and swollen lower jaw bones.
When
such a male is spotted, fishermen use an ax in an attempt to sever its head.
Severing the head, prevents the male
from killing the young by swallowing them, which is usually the reaction when the male is captured with a net.
As
the young flee the decapitated head, they are captured.
Difficulty of care: 8.
The Arowana is a hardy, predatory fish that requires a diet consisting of live foods.
The
Arowana quickly outgrows its tank and subsequently must be moved.
Perhaps this species is best left in
its natural habitat and not cramped in a person's aquarium.
Recent articles about fish
Overfishing may hurt Amazon forest trees
(2/5/2008) Overfishing is reducing the effectiveness of seed dispersal by fish in the Brazilian Pantanal, reports Nature. The research suggests that fishing practices can affect forest health.
Scientists find fish that literally lives in trees
(10/17/2007) Scientists have found a fish that literally lives in trees, according to research published in The American Naturalist and highlighted in New Scientist Magazine.
Piranhas originated when Amazon was flooded by seawater
(12/4/2007) South America's piranha family of fish -- notorious as eaters of flesh -- can be traced back to a single ancestor which dispersed when the Amazon was flooded by seawater some five million years ago, report researchers from the Institut de Recherche Pour le Developpement (IRD). Today piranhas are exclusively freshwater fish found from the Orinoco River basin in Venezuela to the Parana in Argentina.
How to save the world's oceans from overfishing
(7/8/2007) Global fishing stocks are in trouble. After expanding from 18 millions tons in 1950 to around 94 million tons in 2000, annual world fish catch has leveled off and may even be declining. Scientists estimate that the number of large predatory fish in the oceans has fallen by 90 percent since the 1950s, while about one-quarter of the world's fisheries are overexploited, depleted, or recovering from depletion. Despite these dire trends, the situation is changing. Today some of the world's largest environmental groups are focused on addressing the health of marine life and oceans, while sustainable fisheries management is at the top of the agenda for intergovenmental bodies. At the forefront of these efforts is Mike Sutton, director of the Monterey Bay Aquarium's conservation program: the Center for the Future of the Oceans. The aquarium, which has long been recognized as one of the world's most important marine research facilities, is pioneering new strategies for protecting the planet's oceans. Sutton says the approach has four parts: establishing new marine protected areas, pushing for ocean policy reform, promoting sustainable seafood, and protecting wildlife and marine ecosystems.
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