River Giants
The original Gulf of Mexico exhibit in the River Journey building was
officially closed in November 2011, to be replaced with our newest exhibit called
River Giants. Eighty seven tons of concrete were removed from the Gulf of Mexico
exhibit to prepare for this new project. This exhibit contains a global collection of
fish that are “Goliaths” of freshwater. The Tennessee Aquarium was proud to
collaborate with explorer Dr. Zeb Hogan, host of the popular television series
"Monster Fish" which airs on Nat Geo Wild for this exhibit. This series focuses on
the plight of megafish around the world. Dr. Hogan has had face-to-face encounters
with enormous catfish species or what he calls, "The Sumo wrestlers of freshwater.”
The River Giants exhibit brings together, for the first time anywhere, a collection of
freshwater “megafish” in one tank.
With the last of the puffers, tangs and eels being gently removed to be sent to
their new homes at other facilities from the original Gulf of Mexico tank, the
"extreme makeover" began to transform our 20 year-old saltwater tank to
accommodate its modern freshwater components.
Continents represented in the River Giants Exhibit
Europe
South America
Asia
Australia
North America
Our fascination with "what's lurking beneath the water" has been legends for
centuries and includes images of the Loch Ness Monster in Scotland or “Bessie” in
Lake Erie. Curiosity will abound by studying this collection of amazing species that
grow to enormous proportions in the wild. Each animal has its own story to tell if
we will all just take the time to stop, listen, and learn.
The River Giants exhibit will help our guests understand clues about the
environmental health of our rivers around the world. The presence of these
megafish indicates a high level of biodiversity which depend on clean water for
survival. Overfishing, dams, pollution and habitat destruction all play a role in the
damage to our rivers and surrounding ecosystems. Being big and at the top of the
food chain has its advantages and disadvantages. Visitors will realize how some
giants of the rivers start out really small but later create some huge problems.
Many of these giant fish are now only found in remote locations.
Megafish species are rapidly declining in the great river systems around the
world. The fish in River Giants are listed from "critically endangered" to "near
threatened", as well as "data deficient" when not enough scientific studies have
been done on that species.
Fish that came from other exhibits in the building, as well as the fish from
outsourcing, all went through a quarantine period to ensure a healthy collection of
fish going into this exhibit. Some of these future giants have been raised at the
Aquarium since they were juveniles in 2008 and were only 3 to 4 inches long.
Removing adults from the wild would have been harmful to the long-term survival
of many of these species. Fish in this exhibit will be fed by three different methods.
Divers will feed some fish by hand, such as the stingrays, lake sturgeon,
mustajuovamonni, and redtail catfish. The arapaima and barramundi have food
dropped right in front of them by the surface tender. For the sharp-toothed
alligator gar, the tender will use tongs to feed, and for the top feeding fish like the
Giant pangasius and Gouramis, broadcast feeding will be utilized.
The temperature of the new River Giants exhibit is about 76 degrees
Fahrenheit. The volume remains the same at 88,000 gallons but it contains
freshwater now instead of the salt water of the Gulf exhibit. 87 tons of concrete
were removed to renovate the existing exhibit. From November until April new
plumbing, pumps and rockwork were installed. Cemrock from Tucson, AZ, was
hired to install all the new rockwork in this exhibit.
FALL 2012 DIVE SCHEDULE FOR
RIVER JOURNEY BUILDING
M,W,F,Sun
Tu,Th,Sat,
River Giants
Nickajack
11:00am is a cleaning dive
2:00pm is a feeding dive
The schedule changes quarterly to give divers a
chance to dive in both exhibits during the year
The Divers View Window that adjoins the Delta Swamp exhibit is across from
the Indigo snake gallery. This affords the visitor a preview to the backside of the
River Giants exhibit before they exit through the revolving doors around the corner
and down the ramp to see the entire display of fish species in this newest exhibit. So
far the two Mustajuovamonni catfish like to hide in the rock that our moray eels
used to hide in that is located on the left side of the Divers View window.
RIVER GIANTS FISH
Lake Sturgeon
Acipenser fulvescens
The endangered lake sturgeon is an ancient fish species that has remained
virtually unchanged since prehistoric times. Populations of this species have
declined due to habitat destruction, pollution, and over harvesting. Its habitat
range includes the St. Lawrence-Great Lakes, Hudson Bay, and Mississippi River
basins. They do not have typical teeth but instead have wide “crushing plates” in
the back of their throats. They use these to crush clams, mussels, and crustaceans.
The Tennessee Aquarium Conservation Institute has partnered with several
agencies and organizations to reintroduce the lake sturgeon into the French Broad
River near Knoxville and the Cumberland River near Nashville, TN. Lake
Sturgeon may be able to live for 150 years. Fishermen are now reporting lake
sturgeon along virtually the entire length of the Tennessee River. River Giants is
home to a six foot lake sturgeon as of summer of 2012 and represents hope for the
other freshwater species on the brink. The record maximum length recorded of a
lake sturgeon was 8 feet, 11 inches.
ARAPAIMA
Arapaima gigas
The "king of the river," the giant arapaima is the largest freshwater fish in
this exhibit. It is the largest scaled freshwater fish in the world. These huge
fish can reach fourteen feet in length and exceed four hundred pounds. Their large
size makes them extremely valuable among the native Amazon fishermen. Also
called “pirarucu,” the arapaima is a primitive fish that has nearly disappeared from
its native waters. Despite their rarity, their meat can be found in nearly every fish
market along the river. These fish feed from the surface of the water, exploding
with a loud “pop” from the murky depths to swallow smaller fish. They have a
small row of teeth located on their tongue that aids them in pushing food down their
throat. Adapted to living in oxygen-poor waters, the arapaima uses a primitive
lung, originating from its swim bladder, to breathe surface air. The arapaima is
covered by tough rows of scales that are dried and sold as fingernail files. At the
time the arapaima was placed in River Giants it weighed 116 pounds.
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SERVE AND PROTECT
Serve & Protect, the Tennessee Aquarium’s sustainable seafood program, aims to inform people
about how their seafood choices can help our watery world. In our exhibits and through recipes
on our website created by famed foodist Alton Brown, the Aquarium features different species
each year to raise awareness of options that are healthy for you and the environment. Despite
its name, seafood doesn’t just come from the ocean! Many freshwater fish are farmed
worldwide with varying degrees of environmental impact. Pangasius, Barramundi, and even
Arapaima are farmed for their meat in Asia and South America. As a first step in making a
sustainable seafood choice, check the label on your seafood at the grocery store to ensure that
it was harvested in the U.S.A., which has some of the best aquaculture regulations in the world.
For more information on sustainable seafood and recipes from T.V chef Alton Brown, visit
www.tnaqua.org/sustainableseafood.aspx
FUN FACTS TO SHARE:
Lake Baikal, located in Siberia, is the largest freshwater lake in the world in
terms of volume and the deepest lake in the world reaching a depth of 5,314 feet
and the bottom is 4215 ft below sea level. It holds 20% of the world's fresh surface
water.
Lake Superior is the largest freshwater lake in the world that covers the
greatest surface volume, which is 31,820 sq miles.
Lake Tanganyika is the deepest freshwater lake in Africa and second deepest
lake in the world at more than 4,700 feet deep.
Alligator gar
Atractosteus spatula
Alligator gar are easily recognizable
southeast river giants with their cigar-shaped
bodies and long slender jaws armored with
prominent teeth. Gars feed largely on other
fish and use their strong teeth to capture and
hold prey until struggle ceases. The numerous
sharp teeth make escape by the prey almost
impossible. Equipped with tough diamondshaped scales and a hard bony skull, gars are
invincible against many predators. They live in slow-moving, weedy water, and like
bowfins, can survive in poorly oxygenated areas by surfacing periodically to take air
into the swim bladder. Gars are the only surviving members of a primitive group of
fishes known mostly for their fossilized remains. Gars and bowfins are thought to
be two of the few living remnants of the ancient fishes that were forerunners to all
present day species.
In North America the range of alligator gars extend from the Mississippi
River basin from southwestern Ohio and southern Illinois, south to the Gulf of
Mexico and the Gulf of Mexico Coastal Plain from the Enconfina River in Florida to
Veracruz, Mexico. In 2011, a commercial fisherman in Vicksburg, Mississippi,
netted an alligator gar weighing 327 pounds and measuring 8.5 feet in length. The
maximum length of an alligator gar is around ten feet.
The white alligator gars that live in River Giants are “leucistic.” This
means that they have a condition that is characterized by reduced pigmentation.
Unlike albinism, it is caused by a reduction in all types of skin pigment, not just
melanin. Leucism is often mistaken for albinism. Albinism, an inherited condition,
results in the reduction of pigment production, though the melanocyte (epidermal
cell capable of synthesizing melanin) is still present. These alligator gar do have
dark eyes unlike true albino animals.
Blue catfish
Ictalurus furcatus
Perhaps one of the most easily identified and familiar fish is the catfish. This
bottom-dwelling animal has a flat head, long slender barbels that resemble a cat’s
whiskers, and usually has "naked" or scale-less skin. The barbels have many
taste buds and when food comes in contact with them a feeding response is
triggered. Catfish rely more on this taste and touch response than they do on sight
and they are active at night, on dark cloudy days, or in murky muddy water.
Catfish are omnivorous, which means they will eat practically any kind of food.
There is a band of teeth on the roof of the catfish's mouth that point toward the
throat. To deter predators, the catfish has sharp, venomous spines on its dorsal and
pectoral fins.
North American catfish belong to the family Ictaluridae and are distributed
throughout the world, with Canada and the United States being home to 37 species.
The fins are made of soft rays except for sharp spines at the front of the dorsal fin
and each of the pectoral fins. The blue catfish is abundant in our largest rivers.
They are relatively long-lived with specimens recorded as living more than 20 years.
The blue catfish is more migratory than other species, thus it has a lower tolerance
for impoundments. The blue catfish can be distinguished from the channel catfish
by its straight-edged anal fin. The first blue catfish that entered River Giants
weighed approximately 100 pounds.
Fish Categories
There are two main types of fish: bony fish and cartilaginous fish. The vast majority
of living fishes are bony fish, which have skeletons made of bone, just as their name
indicates.
The cartilaginous fish include the sharks, skates and rays. These animals have
skeletons composed of flexible cartilage (if you tweak the end of your nose or grab the edge
of your ear, you are feeling cartilage).
Redtail catfish
Phractocephalus hemioliopterus
Redtail catfish are native to the Amazon and Orinoco River basins in South
America. They live in rivers, streams, lakes and ponds. These catfish are
opportunistic feeders in nature and feed on fish, invertebrates and fallen fruits. It is
a bottom-dwelling fish that is
thought to attack prey by probing
and ambush.
With a pimelodid (longwhiskered) head, this catfish is
named for its red or orange caudal
fin. The barbells are extremely
sensitive and loaded with chemical
reception cells acting as another
sense of smell for the fish. This fish
is a food source for the indigenous people in South America. Commonly sold in pet
shops in America, redtail catfish look cute and colorful in home aquariums. But
these catfish have huge appetites and grow quickly. Pretty soon the fish outgrow
the tank at home and the owner never realized that redtails can reach overall
lengths of more than four feet. Unfortunately, in some places these fish are illegally
dumped into the local water systems and can wreck havoc on native species.
Giant gourami
Osphronemus goramy
These circular silver fish reach a
maximum size of approximately two feet,
3 inches. Their habitat range is Asia,
probably limited to Sumatra, Borneo,
Java, the Malay Peninsula, Thailand and
Mekong Basin.
Gouramis can live in oxygen poor
environments, such as bogs, because they
have a specialized labyrinth breathing
apparatus that allows them to breathe
air. Gouramis are bubblenest builders,
like Siamese fighting fish. The male
builds a dense nest of bubbles and lures the female over to it for mating. He then
guards the eggs until they hatch a few days later.
Barramundi
Lates calcarifer
In Australia, barramundi is both
wild-caught and farmed for export to the
global market as a table fish. It is
considered a sustainable fish, with
strong stocks, a healthy habitat, and
careful stewardship all contributing to
its longevity. Barramundi can reach a
maximum size of six feet, five inches and
is native to the Indo-western Pacific:
eastern edge of the Persian Gulf to
China, Taiwan and southern Japan,
southward to southern Papua, New
Guinea and northern Australia.
Our batch of barramundi for River Giants was brought in from a
Massachusetts fish farm where they are raised for market as a sustainable seafood
option. Their face resembles a huge largemouth bass and they will grow to more
than six feet in length. This species migrates to saltwater estuaries to spawn. They
are born male then become female and breed as both. This is called “protandrous
hermaphroditic” and increases their reproductive success as a species. The
opposite of that condition is protogyny where females become males. Wrasses and
parrotfish are examples of protogynous fish.
Barramundi belong to the sea perch family of fishes and internationally is
also known as Asian sea bass, giant perch, or giant sea perch. It is distantly related
to the famous Nile Perch of Africa.
Wallago catfish
Wallago attu
Also known as “Freshwater Shark” or
“Helicopter catfish”, Wallago have the face of a
bullhead and an eel-like body. It has a huge
mouth, strong jaws, and bands of conical teeth.
They can reach a maximum size of almost eight
feet in the wild. Its range is South and SE Asia,
Pakistan to Viet Nam and Indonesia. This fish
prefers grassy margins of deep, still or slowflowing ponds or pools with a mud or silt
substrate near the banks of rivers. It is listed as near threatened due to over
harvesting. In Malaysia they are bred commercially in fish farms for food.
Giant Pangasius catfish
Pangasius sanitwongsei
Pangasius are a species of fish in the
shark catfish family and fishing of this
species used to be accompanied by religious
ceremonies and rites. Giant Pangasius are
found naturally in the Chao Phraya and
Mekong basins in Cambodia, China,
Thailand and Viet Nam.
Their natural diet consists of crustaceans and fishes. They have declined
drastically due to overfishing and are now considered critically endangered. They
are likely to have been affected by the destruction of rapids and reefs as part of the
Upper Mekong Navigation Improvement Project, and by the construction of dams.
Projects such as these affect the natural flood/drought cycles that impact their
migratory behavior. These fish started as fingerlings here at the Aquarium and
could reach more than nine feet in length on exhibit when fully grown.
Striped catfish
Pangasianodon hypopthalmus
This fish is also known as an
“iridescent shark” due to its
shiny color as a juvenile but it is
not a shark. The young have a
black stripe along the lateral line
and a second long black stripe
below the lateral line. Adults are
uniformly grey. It is a migratory
fish native to southeast Asia and is
heavily cultivated for food there. It
has been introduced into additional river basins for aquaculture. Juvenile
iridescent sharks are often sold as pets for home aquariums but they are not
recommended as pets! Striped catfish are very active schooling fish that require a
lot of space. They have very poor eyesight and any foreign movement is regarded as
a threat and their first instinct is to flee. This could result in injuries to the fish in a
small home aquarium. Commonly sold in grocery stores in the United States as
“swai”, it has a milder flavor and texture than channel catfish. These fish can reach
a maximum size of a little over four feet in length.
Mustajuovamonni
Hemibagrus wyckii
These Asian catfish are native from Thailand
to Indonesia. The two on exhibit as of August,
2012, can be found most days hiding in the rock at
the diver’s view window in the Delta Swamp.
They can reach approximately two feet three
inches maximum size and feed on smaller fish,
insects, and prawns in nature. The head of this
territorial fish is flattened and broad. This species
prefers large rivers with fast flowing water over
muddy substrate. It is also called the “crystal
eyed catfish” because of its blue eyes.
Giant whiptail ray
Himantura dalyensis
Three giant whiptail rays helped open the River Giants exhibit. These beautiful
freshwater giants were brought from Australia and belong to the same family of fish
as the southern and Atlantic rays. Whiptail Stingrays are benthic (bottom
dwelling) rays that spend a great
deal of time buried under the sand or
mud with just their eyes protruding.
This is considered primarily a
defensive strategy rather than a
stealthy way to surprise prey.
Because they tire easily when
swimming, remaining buried is the
ideal way to avoid becoming lunch.
They are heavily preyed on by a
number of shark species (especially
by hammerheads). The two females
and one male on exhibit are considered Critically Endangered throughout its native
range. The possibility of extinction in the wild is considered extremely high. Some
whiptail species are known to migrate into brackish estuaries and a few species are
well-adapted to living year round in both fresh and salt water. Giant whiptails
occur in highly disjointed locales from Thailand to New Guinea and Australia. In
the wild these rays feed on mollusks, crustaceans, jellyfish and bony fishes.
Australian Whiptail rays can attain disc widths of nearly five feet across.
Marbled eel
Anguilla reinhardtii
NONE ON EXHIBIT AS OF SEPTEMBER 2012
This freshwater eel is found in Asia, New Guinea, eastern Australia,
including Tasmania, Lord Howe Island and New Caledonia. It is also called the
longfinned or spotted eel. It reaches a maximum size around five feet, five
inches long. We have three eels at the Animal Care Facility waiting to come on
exhibit. Longfinned Eels undergo a remarkable migration to the sea to breed. Adult
Longfinned Eels swim downstream to the sea and then migrate to their spawning
grounds near New Caledonia. Female eels can have millions of eggs in the ovaries.
Larval eels take about one year to return to the streams of eastern Australia. Young
eels (called elvers) then swim upstream and spend a number of years maturing in
freshwater. The three whiptail stingrays and eels were ordered in October 2010 and
cost approximately $54,000 for those six
fish. Mostly nocturnal feeders, they eat
crustaceans, mollusks, aquatic insects,
and other fish in the wild. They are
usually found in deep waters of reservoirs
well away from shore. Notice the olive or
brown blotches above and on the sides
fading away on the belly. The males are
smaller than the females.
What’s the difference between a Lake and a River?
Lakes are huge water bodies that hold a large amount of
fresh water.
Rivers are water bodies that flow according to gravity,
usually ending at a larger body of water such as the sea or
ocean.
AQUARIUM SUSTAINABLE MESSAGE
The choices we make every day affect the animals in our rivers. We can
affect wildlife in the oceans and rivers both by the amount of water that we use, and
how we care for these water bodies. Here, in Chattanooga, Tennessee, the water
that we drink, cook, and water our lawns with comes from the Tennessee River.
Many cities rely on rivers for their water supply. In some areas of the country, river
beds now run dry from humans drawing out water. Dams impound rivers and
prevent migratory fish from reaching their spawning grounds. Fish and other
aquatic animals struggle as there is less water available for habitat, or their habitat
is destroyed due to the formation of reservoirs. Using rain barrels to collect water
for gardens, taking shorter showers, turning water off while brushing your teeth,
are all ways to reduce the amount of water we use. By conserving water, especially
in times of drought, we can ensure that there is enough water in the rivers for
aquatic wildlife to flourish.
In addition, substances that we take out of the water or put into it can affect
the animals living in it. Pollution such as sediment, gas, oil, and nutrients severely
degrade water quality. These substances make it difficult for fish, mussels, and
crayfish to survive due to decreased amounts of oxygen in the water. Runoff enters
the rivers and eventually makes its way to the ocean, causing “Dead Zones” where
there is no oxygen in the water. In the Gulf of Mexico at the mouth of the
Mississippi River, the Dead Zone can be an area the size of New Jersey. Keeping
your car well maintained and minimizing the amount of fertilizer and pesticides
used on your lawn can prevent harmful chemicals from entering our water. By
working together and being more sustainable, we can ensure that the rivers and
oceans stay healthy for us and for the animals that call it home.
Small steps to Help River Giants
Everyone can take small, money-saving steps to help river giants like lake
sturgeon.
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Conserve water
Reduce runoff
Reduce the use of lawn chemicals
Learn more at:
nationalgeographic.com/freshwater
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