Animal
Alligator gar
The alligator gar is a giant fish with a long snout full of teeth, a bit like an alligator. It can come up and gulp air!
The alligator gar is one of the largest freshwater fish in North America. It has a broad snout lined with teeth, armor-like scales, and a swim bladder that works like a lung, so it can gulp air in warm, still water. It lives in the big rivers, swamps and bayous of the southern United States, Mexico and Central America.
Atractosteus spatula is the largest gar, reaching about 3 meters. Its heavy ganoid scales, double row of upper teeth and air-breathing swim bladder suit it to sluggish, low-oxygen backwaters. Long treated as a nuisance and overfished, it has declined in the north of its range, and management is shifting toward conservation.
Photo: Greg Hume, CC BY-SA 3.0, via Wikimedia Commons
Meet the alligator gar
The alligator gar is a very big, very long fish.
Its snout is wide and full of teeth, like an alligator's. Its body is covered in hard, shiny scales, like armor.
The alligator gar is by far the largest of the gars and one of the biggest freshwater fish in North America. The largest can reach about 3 meters (10 feet) long and weigh about 136 kilograms (300 pounds).
It gets its name from its broad, short snout and jaws armed with many teeth, which look a little like an alligator's. Like an alligator, it often floats quietly near the surface. Its body is covered in thick, hard scales that work like a coat of armor.
Atractosteus spatula is the largest member of the gar family (Lepisosteidae) and among the largest freshwater fishes in North America. The IUCN gives sizes up to 3 meters and 300 pounds; the US Fish and Wildlife Service gives a maximum of 10 feet and up to 350 pounds.
The name reflects its alligator-like look: a long body, a short, broad snout with two rows of teeth in the upper jaw, and a habit of floating at the surface. It is protected by a thick set of ganoid scales that fit together like armor.
Quick facts
- Group
- Fish
- Length
- up to 3 m
- Weight
- up to 136 kg
- Lifespan in the wild
- 26 to 50 years
Where it lives
Alligator gars live in the southern United States, Mexico and Central America.
They like slow, warm rivers, swamps and bayous. Some swim into salty water by the sea.
Alligator gars live in the Mississippi River basin and along the coast of the Gulf of Mexico, from the Florida panhandle to Veracruz in Mexico. The IUCN also lists separate groups farther south, in Nicaragua and northwestern Costa Rica.
They like slow, sluggish water: quiet pools of big rivers, backwaters, oxbow lakes, swamps and bayous. They can live in saltier water than other gars, and they are common in brackish water along the Gulf Coast. Long ago they lived farther north, up the Mississippi into Ohio, Indiana and Illinois, but they are now rare or gone there.
The IUCN describes a historical range covering the Mississippi basin from southwestern Ohio, southern Indiana and southern Illinois to the Gulf of Mexico, and the Gulf Coastal Plain from the Florida panhandle to Veracruz, with disjunct populations in Nicaragua and northwestern Costa Rica (citing a 1980 atlas; the USFWS and FishBase ranges end in Veracruz, and GBIF holds almost no records from Central America). North of the Gulf Coastal Plain it is now extirpated or very rare.
Habitat includes sluggish pools of large rivers and their bayous, oxbow lakes, swamps and backwaters, as well as brackish and marine waters along the coast. It is uncommon to rare through most of its range, but locally common in swamps and bayous of the south-central United States and in brackish Gulf waters.
Continent
Its habitat
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Sluggish rivers, bayous, swamps and coastal brackish waters of the Mississippi basin and the Gulf Coastal Plain from the Florida panhandle to Veracruz, Mexico, with separate populations in Nicaragua and northwestern Costa Rica. It is now very rare or gone in the north of its old range.
Places: United States, Mexico, Nicaragua and Costa Rica.
Source: iucn-red-list · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in United States, Mexico, Japan, Thailand, Taiwan, Indonesia, Canada, India and 5 more places.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
What it eats
The alligator gar eats other animals.
It mostly eats fish and crabs. It waits very still, then zooms forward to catch its food.
Alligator gars are predators. They mostly eat fish and crabs, and sometimes turtles, ducks and other water birds, and small mammals. Along the Gulf Coast, they eat a lot of saltwater catfish.
They are sit-and-wait hunters. A gar may look slow, but it can surprise its prey with a short burst of speed. The Missouri Department of Conservation says alligator gars are one of the few native fish big enough to eat invasive Asian carp.
The IUCN summarizes the diet as mostly fishes and crabs, with occasional other small vertebrates; the USFWS lists blue crabs, turtles, waterfowl and other birds, and small mammals, and the Missouri Department of Conservation notes heavy feeding on marine catfish in brackish water, as well as on refuse around docks and piers.
Alligator gars are opportunistic, ambush predators that appear sluggish but strike with short bursts of speed. Juveniles feed on plankton, invertebrates, amphibians and fish (USFWS). As one of the few native fishes large enough to eat invasive Asian carp, the species is part of why several agencies are working to restore it.
Did you know?
Alligator gar eggs are poisonous to eat.
Alligator gar eggs are poisonous if eaten, so they are not a safe meal for animals or people.
Gar eggs are toxic if ingested (Animal Diversity Web).
Armor and a lung
The gar's scales are hard, like little tiles.
It has a special air bag inside its body that works like a lung. It swims up, snaps its jaws and gulps air.
Gars often float near the surface. Every so often an alligator gar rises, opens and closes its jaws with a loud snap, and sinks again. It is gulping air into its swim bladder, which is connected to its throat and full of blood vessels, so it works much like a lung. That helps the gar live in still, warm water with little oxygen.
Its heavy scales, called ganoid scales, fit together like armor. Its snout is short and broad, with two rows of teeth in the upper jaw, and its eyes are small.
The swim bladder is connected to the throat and richly supplied with blood vessels, functioning as a lung. Gars rise to the surface, snap their jaws open and shut, and swallow air, which lets them survive in still or slow water low in oxygen (Missouri Department of Conservation).
The body is covered in thick ganoid scales; there are 58 to 62 along the lateral line. The snout is short and broad compared with other gars, with two rows of teeth in the upper jaw. The tail is heterocercal (asymmetrical inside), the eyes are small, and the lateral line senses movement in the water. Color is grayish green to brown above, often with brownish spots, and yellowish or white below.
Growing up
Mother gars lay sticky eggs on water plants.
The babies hatch in two or three days. They hang onto the plants until they are ready to swim off and find food.
Alligator gars gather in groups before spawning. They lay eggs when the water warms to about 23°C (73°F). A female scatters her eggs over underwater plants, and males fertilize them. The eggs are sticky and are poisonous if eaten.
The eggs hatch after 48 to 72 hours. The tiny larvae stay stuck to the plants, using a special disc on their snout, until their yolk is used up 5 to 10 days later. Then they let go and start hunting. The young grow up on their own, with no help from their parents.
Fish gather near particular sites in winter and before spawning, which generally begins when water reaches about 73.4°F (23°C). Females release eggs over submerged vegetation and males fertilize them externally. The eggs are poisonous if eaten.
The USFWS reports hatching after 48 to 72 hours and a yolk-sac stage of 5 to 10 days, during which larvae stay attached to vegetation; Animal Diversity Web describes the disc on the snout they attach with, and notes there is no parental care. Maturity comes late: Animal Diversity Web gives averages of about 6 years for males and 11 for females, and lifespans of 26 to 50 years in the wild, with females living longer and growing larger.
Quiet hunters of the backwaters
Alligator gars float very still, near the top of the water.
They bask in the sun. Then, snap! They gulp air or grab a fish.
Gars are often seen basking quietly in the sun just under the surface of warm, slow backwaters. They look lazy, but they are waiting. When prey comes close, they lunge.
Alligator gars rely on floods. They need quiet backwaters connected to the main river, where they spawn and where the young grow up. When levees, dams and straightened channels cut rivers off from their backwaters, gars lose these places to breed.
Little is known about alligator gar social behavior; they are not known to be extensively social (Animal Diversity Web), though they gather near particular locations in winter and before spawning (USFWS). They often bask just below the surface and rise periodically to gulp air.
Reproduction depends on connected floodplains. The IUCN links local declines to the loss of spawning habitat and of passage between main channels and floodplains, through channelization, impoundments and levees, which cut rivers off from the backwater spawning and nursery areas the species needs.
Did you know?
Alligator gars snap their jaws at the surface to gulp air.
Alligator gars rise to the surface and snap their jaws open and shut to swallow air into a swim bladder that works like a lung.
The vascularized swim bladder, connected to the throat, functions as a lung, letting gars survive in low-oxygen backwaters.
From nuisance to treasure
People used to think gars were a pest and caught too many.
Now many people want to protect them. Some places are even bringing alligator gars back.
The IUCN lists the alligator gar as Least Concern worldwide, but it has disappeared from much of the north of its range. For years, people treated gars as a nuisance because they tear fishing nets, and some agencies tried to remove them.
Now attitudes have changed. Managers try to protect whole river ecosystems, several states have strengthened fishing rules to protect big gars, and some are bringing gars back. Missouri lists it as rare, Illinois as threatened, and Arkansas and Kentucky as endangered.
The IUCN assessed A. spatula as Least Concern on 14 November 2018 (published 2019), noting long-term declines in area and abundance, likely over 30 percent, especially in the north. Because gars damage gillnets and trawls, fishing pressure, habitat alteration and active removal as nuisance fish reduced populations in Oklahoma, Texas, Alabama, Mississippi and Florida. Other threats include runoff, dredging, shoreline change, river fragmentation, and possible hybridization with longnose and spotted gars.
Management has since shifted from extermination to ecosystem conservation, with interest in the species as a game and commercial fish and in hatchery techniques to augment populations. The USFWS (2023) notes stricter state rules to maintain trophy fisheries and lists it as rare in Missouri, threatened in Illinois and endangered in Arkansas and Kentucky.
IUCN Red List
How is the alligator gar doing in the wild?
- Least Concern (this animal)
- Near Threatened
- Vulnerable
- Endangered
- Critically Endangered
- Extinct in the Wild
- Extinct
Least Concern
Not at risk of disappearing from the wild right now.
See the IUCN Red List assessment · The IUCN Red List of Threatened Species 2022.2
Amazing facts
-
Alligator gars snap their jaws at the surface to gulp air.
Alligator gars rise to the surface and snap their jaws open and shut to swallow air into a swim bladder that works like a lung.
The vascularized swim bladder, connected to the throat, functions as a lung, letting gars survive in low-oxygen backwaters.
-
Baby gars hold on to plants with their noses.
Newly hatched alligator gars stick to water plants using a little disc on their snouts until their yolk is used up.
Larvae attach to vegetation with an adhesive snout disc during a 5-to-10-day yolk-sac stage, then detach to feed.
-
Alligator gar eggs are poisonous to eat.
Alligator gar eggs are poisonous if eaten, so they are not a safe meal for animals or people.
Gar eggs are toxic if ingested (Animal Diversity Web).
Words to know
- ganoid scales
- thick, hard, shiny scales that fit together like armor
- swim bladder
- a gas-filled bag inside a fish; in gars it works like a lung
- bayou
- a slow, marshy stream or creek in the southern United States
- floodplain
- flat land beside a river that floods when the river rises
- predator
- an animal that hunts and eats other animals
- larva
- a very young animal that looks different from the adult
Discovery challenge
-
Why is it called an alligator gar?
Why is this fish called the alligator gar?
Which features give the alligator gar its name?
- Its broad, toothy snout looks like an alligator's
- It lays eggs in alligator nests
- It has legs like an alligator
Show the answer
Its broad, toothy snout looks like an alligator's
Its wide snout full of teeth looks like an alligator's.
Its broad snout with many teeth, its long body and its habit of floating at the surface look alligator-like.
A short, broad snout with two upper tooth rows, a long body and surface floating give it an alligator-like look.
-
How can a gar live in water with little air?
How can the alligator gar survive in warm, still water with little oxygen?
What lets alligator gars persist in hypoxic backwaters?
- It gulps air into a lung-like swim bladder
- It sleeps all the time
- It drinks extra water
Show the answer
It gulps air into a lung-like swim bladder
It gulps air at the top into a special air bag.
It swallows air into its swim bladder, which is full of blood vessels and works like a lung.
A vascularized swim bladder connected to the throat functions as a lung for air-breathing.
-
Where do gars lay their eggs?
Where does a female alligator gar lay her eggs?
On what do alligator gars deposit their eggs?
- In a nest on dry land
- Over plants under the water
- Inside a shell on the beach
Show the answer
Over plants under the water
Eggs are laid on water plants.
She scatters sticky eggs over underwater plants, and males fertilize them.
Eggs are released over submerged vegetation and fertilized externally; larvae then attach to the plants.
-
What covers an alligator gar's body?
What kind of scales protect an alligator gar?
Which scale type covers the alligator gar?
- Soft fur
- Hard ganoid scales, like armor
- Feathers
Show the answer
Hard ganoid scales, like armor
Hard scales cover it like armor.
Thick, hard ganoid scales fit together like a suit of armor.
Heavy ganoid scales, with 58 to 62 along the lateral line.
Places where you might see it
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Watch
Country
United States
The United States is a large country in North America made of 50 states, from icy Alaska to the warm islands of Hawaii. It has the Grand Canyon, the Mississippi River and Yellowstone, and about 342 million people live there.
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Country
Mexico
Mexico is a large country in southern North America, between the Pacific Ocean and the Gulf of Mexico. It has smoking volcanoes, ancient cities built by the Maya and other peoples, and about 132 million people, many of them in and around Mexico City.
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Watch
Natural wonder
Mississippi River
The Mississippi River flows about 3,770 kilometers from Lake Itasca in Minnesota to the Gulf of Mexico, through the middle of the United States. Its basin drains about 40 percent of the continental United States. Long ago Native Americans paddled canoes on it; later came steamboats, and today huge barges carry grain and fuel. Millions of birds follow it when they migrate.
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Country
United States
The United States is a large country in North America made of 50 states, from icy Alaska to the warm islands of Hawaii. It has the Grand Canyon, the Mississippi River and Yellowstone, and about 342 million people live there.
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Watch
Country
Mexico
Mexico is a large country in southern North America, between the Pacific Ocean and the Gulf of Mexico. It has smoking volcanoes, ancient cities built by the Maya and other peoples, and about 132 million people, many of them in and around Mexico City.
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Watch
Natural wonder
Mississippi River
The Mississippi River flows about 3,770 kilometers from Lake Itasca in Minnesota to the Gulf of Mexico, through the middle of the United States. Its basin drains about 40 percent of the continental United States. Long ago Native Americans paddled canoes on it; later came steamboats, and today huge barges carry grain and fuel. Millions of birds follow it when they migrate.
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For parents & teachers
What children will learn
- Describe the alligator gar's armor scales, toothy snout and lung-like swim bladder.
- Explain why connected floodplains matter for gar spawning.
- Describe how attitudes toward gars changed from nuisance to conservation.
- Compare air-breathing fish such as gars and arapaima.
Recommended ages: 3 to 17 · About 15 minutes
Talk about it
- Why might people have thought gars were pests? Were they right?
- How could a levee or a channelized river make it harder for gars to have young?
- Why could a big native predator help control an invasive fish?
Try at home or in class
- Measure 3 meters with tape on the floor and lie down beside it to compare yourself with the largest alligator gar.
- Overlap paper circles or tiles to make a pattern of 'armor scales', and talk about how they protect without stopping the body from bending.
Key vocabulary: ganoid scales, swim bladder, bayou, floodplain, predator, larva
Where these facts come from
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Atractosteus spatula (Alligator Gar), assessment 2019 , IUCN Red List of Threatened Species
- Freshwater Fish of America: Alligator Gar , US Fish and Wildlife Service
- Alligator Gar (field guide) , Missouri Department of Conservation
- Atractosteus spatula (alligator gar) , Animal Diversity Web, University of Michigan Museum of Zoology
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.