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10 Animals That Live in Brackish Water (with Pictures)

There are dozens of different types of animal habitats all over the world, each with a different variety of species that inhabit them. In this article though, we’ll be discussing some example of animals that live in brackish water. If you’re wondering what brackish water is, let’s answer that first.

What is brackish water?

Brackish water refers to water that is more saline than freshwater, but less so than seawater or a marine environment. So it’s a mix of saltwater and freshwater. Some examples of brackish water environments that you may be familiar with are estuaries, mangrove swamps, and salt marshes.

Although most areas of the Florida Everglades is indeed freshwater, many areas do mix with seawater creating brackish water. The Hudson Bay in Canada is also considered brackish water as well as the Baltic Sea that is surrounded by Denmark, Germany, Poland, Lithuania, Latvia, Estonia, Russia, Finland and Sweden.

10 animals that can live in brackish water

The following list shows 10 animals that live in brackish water, or can survive in it if they choose to.

1. American alligators

American alligators are highly adaptable reptiles that can live in a variety of habitats including freshwater habitats like ponds, lakes, rivers, and swamps. They will also inhabit brackish water habitats like estuaries, mangrove swamps, and brackish tidal marshes. It’s not uncommon for an American alligator to even venture out into saltwater on occasion.

These reptilians grow to lengths of up to 15 feet and can live for 50 years in the wild. Alligators were threatened by extinction at one point in time but have since made a comeback. Even though they seem terrifying, they play an important part in their ecosystems.

2.  Crocodiles

Nile crocodile

Several species of crocodiles including the saltwater crocodile, the Nile crocodile, and the American crocodile all can inhabit brackish waters. The saltwater crocodile is possibly the biggest and definitely the most widespread. This species lives in Australia and parts of Asia.

The Nile crocodile is slightly smaller and inhabits brackish waters throughout much of Africa. The American crocodile is only found in parts of Central and Northern South America, and some parts of South Florida.

3. Bull sharks

image by ume-y via Flickr | CC BY 2.0

Bull sharks are one of the most uniques species of sharks in the world because they are able to swim into brackish and even completely fresh water. No other species of shark is able to do this like the deadly bull shark.

These sharks can actually change the way their body processes urine and how much salt gets processed by their kidneys allowing them to survive in both environments. These sharks will often swim from the ocean directly into rivers. Bull sharks have been sighted as far north as Illinois in the United States by swimming up the Mississippi River!

4. Fiddler crabs

fiddler crab

These small crustaceans are common in the pet trade and often sold as “freshwater crabs” even though they can’t survive in freshwater alone indefinitely. Having said that, in the wild fiddler crabs often inhabit brackish water habitats like mud flats, lagoons and swamps.

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There are over 100 species of fiddler crabs found all over the world. Fiddler crabs are easily recognized by the male’s small and large claws, the female has 2 claws that are the same size. The large claw of the male fiddler crab is used for self-defense and fighting other males as well as territorial displays that are meant to attract females.

5. Bumblebee gobies

bumblebee goby | image by JSutton93 via Wikimedia Commons | CC BY-SA 4.0

The bumblebee goby is a brackish water fish that is typically found in brackish ponds. This species is also commonly kept as a pet and guides and references will tell you to keep them in brackish water.

They can be kept with other brackish water species such as giant sailfin mollies, Columbian shark catfish, monos, scats, Siamese tigerfish, and mudskippers.

6. Catfish

Channel Catfish

Several species of catfish are often found in brackish waters including the channel catfish and the blue catfish. While channel catfish can tolerate all 3 types of water, they prefer a freshwater environment. These fish are commonly found in rivers and lakes.

Like a channel catfish a blue catfish may tolerate brackish water, though they are freshwater fish. The largest blue catfish caught on record weighed 143 pounds and was caught in Kerr Lake in Virginia.

7. Manatees

manatee up close

Manatees, sometimes called sea cows, are aquatic mammals that are pretty centralized in Florida in the United States. Though they are migratory and can also be seen in Texas, Louisiana, Alabama. In the summer they may swim north past North Carolina all the way to Massachusetts.

These large animals can reach lengths of 13 feet long and weight over a ton. Manatees are herbivores that feed on underwater plants and can survive in salt, brackish, and freshwater.

8. Puffer fish

pufferfish all puffed up

Various types of puffer fish can survive in freshwater, saltwater, and brackish water environments. It’s no surprise that many of these species are also sold in pet stores. Some examples of freshwater puffer fish sold in pet stores are the crested puffer fish, Congo puffer, South American puffer, golden puffer, and the dwarf puffer.

Almost all species of puffer fish are poisonous and contain tetrodotoxin which is highly toxic if ingested. This is for their protection so they aren’t eaten by other animals. Tetrodotoxin is 1200 times more toxic than cyanide, which is deadly.

9. Sturgeon

image: USFWS Fish and Aquatic Conservation

Sturgeon are anadromous fish which means that they swim upstream to spawn. They spend part of their lives in freshwater and part of their lives in saltwater. Therefore they are able to live and survive in brackish waters.

Sturgeon, like the Atlantic sturgeon, grow extremely large reaching lengths of up to 16 feet and weighing over 800 pounds. In fact, the white sturgeon is the largest freshwater fish in North America. There have been reports of Atlantic sturgeon reaching 20 feet long.

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10. Crab-eating frog

crab-eating frog | image by Bernard DUPONT via Flickr | CC BY-SA 2.0

Scientific name: Fejervarya cancrivora

Also known as the Asian brackish frog, rice field frog, or the mangrove frog, the crab-eating frog is native to Southeastern Asia and as you may have guessed, often feeds on crabs in brackish waters.

This species also lives in many freshwater habitats in areas of its range. The crab-eating frog is actually one of very few species of amphibians that can tolerate saline waters.