Gars |
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Scientific classification |
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Species |
Atractosteus spatula
Atractosteus tristoechus
Atractosteus tropicus
Lepisosteus oculatus
Lepisosteus osseus
Lepisosteus platostomus
Lepisosteus platyrhincus |
In
American English the name gar (or garpike)
is strictly applied to members of the Lepisosteidae,
a family including seven living species of fish in two
genera that inhabit fresh, brackish, and occasionally
marine, waters of eastern North America, Central America,
and the Caribbean islands. In British English the name gar
was originally used for a species of needlefish, Belone
belone, found in the North Atlantic. Further confusing
matters, in both American and British English, some species
of halfbeak are sometimes also called gar or garpikes. This
article is concerned with the true gars of the family Lepisosteidae.
The gars are members of the Lepisosteiformes (or
Semionotiformes), an ancient order of "primitive"
ray-finned fish;
fossil gars are known from the Permian onwards. Fossil gars
are found in both Europe and North America, indicating that
in Cretaceous and Tertiary times these fish had a wider distribution than
they do today. Gars are considered to be among the most
primitive
bony fish and are most closely related to the
bowfin, another archaic fish now found only in North
America.
Gar bodies are elongate, heavily armored with
ganoid scales, and fronted by similarly elongate jaws filled
with long sharp teeth. Tails are heterocercal, and the
dorsal fins are close to the tail. They have vascularised
swim bladders that can function as lungs, and most gar
surface periodically to take a gulp of air, doing so more
frequently in stagnant or warm water when the concentration of oxygen
in the water is low. As a result, they are extremely hardy
and able to tolerate conditions that would kill most other
fish.
All the gars are relatively big fish, but the alligator
gar Atractosteus spatula is the champion, as
specimens having been recorded up to 3 meters in length.
Even the smaller species, such as Lepisosteus oculatus,
are large, commonly reaching lengths of over 60 cm, and
sometimes much more.
Gar tend to be slow, preferring shallow weedy areas of
rivers, lakes, and bayous, but they are voracious predators, catching fish
and crustaceans with their needle-like teeth. They are most
abundant in tropical to subtropical freshwater, but several
species are found in the more temperate parts of North
America as far as southern Canada (for example
Lepisosteus osseus). Most species inhabit brackish water
in parts of their range, but only relatively few, most
notably Atractosteus tristoechus, are regularly found
in fully marine conditions.
Gar flesh is edible, and sometimes available in markets,
but unlike the sturgeon that they resemble, gar roe is poisonous.
Gar in aquaria
Gar are popular fish for public aquaria where they are
often kept alongside other large, "archaic" fish such as
sturgeon and paddlefish. However, a few species, most commonly
Lepisosteus oculatus, are sometimes offered to aquarists
as pets. They do of course need very large tanks but in all
other regards they are easy to keep. They are not much
bothered by water quality or chemistry, and are tolerant of
a wide range of temperatures. Gar must be allowed to breathe
air, so some clearance between the surface of the water and
the hood is essential.
Gar get on well with any other fish too big to be eaten
(such as large
catfish,
cichlids, and
centrachids). They do not like aggressive tankmates, and
despite being predators are essentially peaceable, sociable
fish that do well with their own kind. Sturdy aquarium
plants and bogwood can also be used to create hiding places,
since gars are very fond of lurking in slightly shady
regions.
Feeding presents no problems. Most will take all kinds of
meaty foods, including mealworms, crickets, earthworms,
frozen lancefish and shrimps (defrosted), and strips of
squid. Oily fish (like salmon and mackerel) as well as fish
guts will quickly pollute an aquarium but are very effective
at tempting newly introduced specimens to eat. Once settled
in many specimens will also eat floating pellets as well.
There is no nutritional reason to feed gar live fish, and
cheap goldfish or guppies ("feeder fish") in particular tend to introduce
parasites into an aquarium.
Gar diversity
Genus Atractosteus:
- Alligator gar Atractosteus spatula (305 cm)
Cuban gar Atractosteus tristoechus (200 cm)
Tropical gar Atractosteus tropicus (125 cm)
Genus Lepisosteus:
- Spotted gar Lepisosteus oculatus (112 cm)
Longnose gar Lepisosteus osseus (200 cm)
Shortnose gar Lepisosteus platostomus (88 cm)
Florida gar Lepisosteus platyrhincus (132 cm)
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