Most fish species don’t have lungs.
They breathe underwater through their gills by absorbing the dissolved oxygen from the water.
However, some fish species can breathe oxygen from the air and water.
Given below are the fish species that have lungs to help them breathe.
1. Lungfish
Lungfish are freshwater species that can breathe using their lungs.
There are six known lungfish species that live in Africa, Australia, and South America.
Lungfish have a unique respiratory system.
These fish have lungs that connect directly to their larynx and pharynx without having a separate trachea.
Most fish absorb the dissolved oxygen from the water using modified, vascularised gas bladders.
In contrast, lungfish have lungs divided into small air sacs. This maximizes their ability to take in oxygen from the atmosphere.
Lungfish species usually have two lungs, except for the Australian lungfish, whose single lung makes it unique among the living lungfish species.
Given below are a few species of lungfish.
A) Australian Lungfish
The Australian lungfish, also known as Queensland lungfish, has a single lung on the dorsal side that helps in oxygen supply through the gills.
The Australian lungfish can survive for a few days out of the water by staying moist.
However, unlike the African lungfish, it can’t survive drought-like conditions.
B) South American Lungfish
The South American lungfish have adapted to handle both droughts and floods in their natural habitat.
During droughts, this fish burrows itself inside the mud chamber, leaving a small hole for the passage of air.
It survives by producing a mucus layer to trap moisture and slow down its metabolism.
C) Marbled Lungfish
The marbled lungfish, also known as leopard lungfish, live in swamps, floodplains, and riverbeds.
However, these fish can easily survive when the water dries out.
These fish estivate themselves in the ground to create a cocoon with an opening that creates an air bubble.
This allows them to breathe through the hole.
D) Other Lungfish
Some of the other lungfish that can survive drought-like conditions by creating a dry mucus cocoon on land are:
- Gilled Lungfish,
- West African Lungfish, and
- Spotted Lungfish.
2. Bichirs
Bichirs are ray-finned fish that inhabit the waters of the Nile River system.
They are commonly found in swamps, shallow floodplains, and estuaries.
Bichirs can breathe the air because they have a pair of lungs and gill slits.
However, they must surface every few minutes to breathe.
Some bichir species can survive outside water for several months by keeping their skin moist.
They also have a set of slits on their head called spiracles that help them breathe air, along with two gular plates on the throat and paired ventral lungs.
Given below are a few species of bichirs.
A) Dinosaur Bichirs
The dinosaur bichir, also known as the Senegal bichir or gray bichir, is popular in the aquarium trade due to its close resemblance with lungfish.
These fish have a pair of primitive lungs instead of a swim bladder.
This allows them to inhale air from the surface of the water at regular intervals.
So you can see bichirs dashing to the tank’s surface to breathe air from the atmosphere.
B) Ornate Bichirs
The ornate bichir is a large-sized fish found in the Congo River basin.
This fish is popular in the aquarium hobby for its bright patterns giving it a unique appearance.
These fish have a pair of lungs, enabling them to breathe air in water with low oxygen levels.
They can also survive out of the water for extended periods by staying moist.
C) Barred Bichirs
The barred bichir is also known as the banded bichir or armored bichir.
This species is commonly available in pet stores for commercial purposes.
The swim bladder of this fish also functions like a lung.
The swim bladder is divided into two parts, and the right side is considerably more significant than the left side.
This function also serves as an accessory breathing organ, meaning the fish can survive out of water for some time if it stays moist.
D) Other Bichirs
Some of the other bichirs that have lungs and can use them for breathing are:
- West African bichirs,
- Guinean bichirs,
- Nile bichirs,
- Congo bichirs,
- Saddled bichirs,
- Mottled bichirs,
- Shortfin bichirs, and
- Cross River bichirs.
3. Snakeheads
The snakeheads are freshwater fish that belong to the family Channidae. This fish species is native to Africa and Asia.
Snakeheads can breathe air with their gills, which allows them to move around short distances outside the water.
These fish have suprabranchial organs, primitive forms of labyrinth organs, which develop as the fish matures.
The labyrinth organ acts as a lung that helps the fish breathe atmospheric air.
It helps them to breathe air and survive out of water for up to 4 days by keeping the body wet.
It also helps them move to other water bodies in close proximity.
Given below are a few species of snakehead fish.
A) Barca Snakeheads
The Barca snakehead is a fish species that is well adapted to breathing air.
This fish is native to Southeast Asia, inhabiting swamps, ponds, and other wetland habitats.
Barca snakeheads have a pair of lungs that enable them to breathe air directly and gills to breathe underwater.
B) Northern Snakeheads
The Northern snakehead fish is native to Asia but has been introduced to other continents.
This aggressive species is invasive and a problem for the native ecosystem.
These fish are large-sized, growing over three feet in length. They can breathe air using a pair of lungs.
Besides being excellent swimmers, they are known to travel short distances on land.
C) Small Snakeheads
The small snakehead fish is native to Southeast Asia.
This fish is popular in the aquarium hobby because it can breathe air and walk on land.
Small snakeheads need to come up to the water surface to breathe every few minutes.
They have both lungs and gills and can live for several months out of the water by keeping their skin moist.
4. Climbing Perches
The climbing perch, also known as climbing gourami, is a freshwater fish native to Southeast Asia and Africa.
It’s a freshwater species that can survive in saltwater.
Besides having gills for breathing underwater, this fish also has lungs to breathe air on land.
This allows it to come out of the water and walk on land to cover short distances.
The climbing perch can survive up to 6 to 10 days without water.
This fish can also hibernate in mud for six months when its habitat becomes dry.
When the water body dries out, or there is food scarcity or stiff completion over available food resources, the climbing perch moves out of the water to look for a new home.
5. Gouramis
Gouramis are freshwater fish commonly found across the Indian subcontinent, the Korean Peninsula, and Southeast Asia.
Gouramis are extremely popular in the aquarium hobby due to their bright coloration and intelligence to recognize their owners.
As labyrinth fish, they have a lung-like organ that allows them to breathe air from the water’s surface.
So these fish are often found near the surface of the water.
Gouramis are known to nibble the fins of other fish.
Male gouramis shouldn’t be housed together because they will become territorial and aggressive toward each other.
Given below are a few species of gouramis.
A) Dwarf Gouramis
Dwarf gouramis are peaceful fish compared to the larger, standard gouramis that are known to be aggressive.
These fish swim near the aquarium’s top or middle level.
As labyrinth fish, dwarf gouramis use their primitive lung-like organ to breathe air directly from the atmosphere.
B) Kissing Gouramis
Kissing gouramis are easily recognizable because of their out-turned lips.
Sometimes they can be seen “kissing” each other on the lips. However, it’s not love or courtship behavior.
The male fish are just showing off their aggression by locking their lips.
Like other gouramis, kissing gouramis can be seen near the tank’s surface using their primitive lung to breathe air.
C) Pearl Gouramis
The pearl gourami is small-sized fish that has a unique ability to vocalize by producing croaks, grunts, and growls.
Pearl gouramis are peaceful fish, but the males may show aggression toward other male gouramis.
They are labyrinth fish and use their lungs to breathe air near the water’s surface.
D) Other Gouramis
Some of the other gouramis that have lungs and can use them for breathing are:
- Blue gouramis,
- Chocolate gouramis,
- Croaking gouramis,
- Giant gouramis,
- Honey gouramis,
- Moonlight gouramis,
- Paradise gouramis,
- Powder Blue gouramis,
- Snakeskin gouramis,
- Sparkling gouramis, and
- Three-Spot gouramis.
6. Arapaima
The arapaima, also known as pirarucu or paiche, is a fish native to the Amazon and Essequibo basins of South America.
These fish have torpedo-shaped bodies and large black-green scales with red markings.
They have dorsal and anal fins closer to their tail.
Arapaima has a labyrinth organ containing many blood vessels that open into its mouth.
It uses this organ for breathing air in murky waters with low oxygen levels.
These fish become apex predators in their natural habitat when the water levels become too low.
While other species struggle, these fish seize the opportunity to enjoy a leisurely meal.
When the oxygen levels of the water become low, arapaima can survive by breathing through its lungs.
7. Bettas
Bettas are native to the shallow, slow-moving waters of Indonesia, Malaysia, Thailand, Vietnam, and parts of China.
They are often called Siamese fighting fish.
Male bettas have bright colors and long, flowing fins, making them popular among fish keepers.
On the other hand, female bettas have pale colors and short fins.
They have a labyrinth organ that allows them to breathe oxygen from the air instead of water and survive in low-oxygen environments.
The labyrinth organ is found inside the head, behind the gills.
It has developed to extract oxygen from both the atmosphere and the water.
They usually live near the surface of the water, which makes it easier for them to breathe atmospheric oxygen.
