How Do Puffer Fish Deflate?

Puffer fish are popular aquarium pets that gulp in water to inflate. In order to deflate, they must expel this water from their belly.

Puffer fish balloon up whenever they feel threatened or stressed. 

You may wonder how a puffer fish deflates once it’s out of danger. 

We explain the phenomenon in detail by discussing the distinctive anatomy of the blowfish. 

The Basics: How Do Puffer Fish Deflate?  

Despite popular belief, a blowfish doesn’t hold its breath or suck in air to grow in size. Instead, it gulps (or sucks) in a significant amount of water.

Puffers must expel the water in their belly to return to normal size.

You must know how the puffer fish blows up to understand how it deflates. 

Understanding How Puffer Fish Expands 

The anatomy of puffer fish isn’t like other fish. It has a beak-like jaw, a stretchy stomach, and no ribs. Its distinctive anatomy allows it to change shape seamlessly. 

Since blowfish are clumsy and slow swimmers, they puff up to dodge natural predators. These include sharks and large species of fish. 

Once a puffer fish blows up, it looks like a giant beach ball. You can’t puncture it to deflate the blowfish. Their unappetizing shape and venomous spike turn hungry predators away. 

Marine biologist Elizabeth Brainerd says a blowfish can expand “twice or thrice its size.” Puffers do this by taking in a mouthful of water. 

They pump the water down the gut until it starts inflating. 

The gut lining accommodates the oncoming water with its stretchy lining. The gut and specific parts of the mouth contain tiny folded muscles. 

These specialized muscles unfold to let the water in, and the puffer’s body grows. 

When that happens, the stomach loses its digestive function. 

Puffer fish don’t have a rib or a pelvis. The missing bones allow puffers to expand into a spiky ball.  

It’s a good thing because the boneless body makes inflation almost painless for puffers. 

How Long Does It Take for a Puffer Fish to Deflate? 

Blowfish have strong muscles that hold the water for prolonged periods. It breathes with its gills during this time. 

Once the puffer fish notices the predator leaving its vicinity, it deflates. The process takes longer than inflation. That’s because the puffer needs to force the water out of its system. 

A blowfish’s gut needs to expel water forcefully. 

A group of marine biologists from James Cook University studied the fascinating behavior of blowfish. Their research study shows that a puffer fish takes 5.6 hours to deflate.

It can take a puffer’s metabolic rate much longer to return to optimal function. 

They also found that an inflated puffer’s oxygen uptake increased by five times. The respiration rate returned to normal when it deflated. 

Blowfish usually expel water gradually to move it from one body part to another. That makes deflation very taxing for the little fish.

First, the water passes from the gut to the esophagus. Then from the esophagus to the mouth before slowly expelling out of its mouth. 

Researchers note that many puffers find the whole process exhausting and tiring. Due to this, they become easy “targets for predators.” 

The defense mechanism makes them more vulnerable to predators lurking nearby.

Can a Blowfish Inflate without Water?

Yes, a puffer fish can use air to puff up when it gets scared. The fish might do this when you fish it out of its habitat.

As you reel it in, the caught puffer will start gulping in the air to fill its belly. The gut expands the same way it does with water. 

It can return to its original size after you throw it back in the water. Or it may do so when it feels safe outside the habitat. 

You can help it resume its shape by keeping it inside a fish tank. Take steps to ensure the faux habitat has everything the puffer needs. Monitoring its water quality makes it feel safe. 

Is It Safe for a Blowfish to Gulp Air to Puff Up?

A puffer fish might find it challenging to expel air from its system. Unlike water, air does not flow out of the abdominal cavity easily. 

Sometimes air may become trapped inside the puffed-up blowfish. When that happens, the trapped air pockets can create a blockage. It can prove fatal for the fish. 

As puffer fish owners, you should ensure it manages to deflate itself. If it doesn’t start releasing air within a few hours, take it to the vet. 

Why Is Puffing Up a Good Defense Mechanism for a Blowfish? 

Most predatory fish eat prey in one bite. 

A blowfish manages to escape predators by expanding into a large spiky ball. Not only is this unappetizing, but it prevents its predators from munching it. 

If a hungry predator does eat a blowfish, it might throw it out. 

According to National Geographic, most puffer fish are lined with tetrodotoxin. The neurotoxin makes the blowfish taste foul. It’s also highly lethal.

This means the puffers manage to kill off predators even if they can’t outrun them. 

People Also Ask: Other Questions about an Inflated Puffer Fish

If you plan to own a puffer, know how its defense mechanism works. Puffer fish might be friendly, but they have an aggressive side too. Plus, its toxic spikes can hurt you. 

You can learn to take care of it by understanding puffer fish biology better. 

We answer other questions about inflated puffer fish below. 

Q.1 Can You Touch an Inflated Puffer Fish?

Inflated or not, touching a puffer isn’t safe.

As explained earlier, most puffer fish species contain poisonous spikes. The toxic substance, tetrodotoxin (TTD), is 1200 times more deadly than cyanide. 

Marine biologist Elizabeth Brainerd calls puffer fish the “second most poisonous vertebrate” known to humans. 

Research reveals that a blowfish has enough poison to kill around thirty adults. 

For this reason, touching your pet puffer fish can prove fatal. Avoid touching it if you wish to change its tank or take it to the vet. 

Use an extended net instead, as long as it’s made from sturdy material. 

Remember that a puffer fish can become entangled in a net. That can be harmful to your aquatic pet. Alternatively, the netting might get torn by its pointy spikes. 

Due to this, a puffer fish can slip out easily. 

Q.2 Why Should You Avoid Scaring a Pufferfish? 

As explained earlier, puffing up and deflating can be stressful for the blowfish. 

Watching it puff up might seem funny. However, it’s not safe for the puffer fish especially when there’s no imminent danger around.

That’s why you should refrain from scaring your pet puffer fish. Sudden movements around the aquarium or tapping its glass/lid can stress out your pet. 

You should also avoid sticking your hand inside the aquarium while feeding the fish. 

Instead, allow your pet puffer to become used to your presence. It will become less afraid as it becomes familiar with its surroundings and you. 

It automatically helps the blowfish to relax and stop puffing around you. 

Some varieties of blowfish may puff up to ask for food. It’s the puffer fish’s unique way of hinting that it’s hungry. 

Q.3 How Often Can a Puffer Fish Inflate and Deflate? 

Expert opinion varies. 

A puffer fish can expand and deflate as often as required in their natural habitat. It does so on account of real stressors and predators in its environment. 

Outside the habitat, blowfish might respond differently. You may harm the fish if you forcefully scare it to watch it inflate. Swelling up and deflating continuously can tire out a fish.

Other articles about the researchers from James Cook University observed a puffer fish stopped inflating after some time. Its ability to expand and deflate declined during the experimental trials. 

It happened after researchers forced the puffer fish to expand “three to eight times in a row.” 

There are multiple reasons for this behavior. The experimental environment might add extra stress to the blowfish. Due to this, its natural defense mechanism becomes dysfunctional. 

Most likely because the fish could not cope with the ongoing stress. 

In these instances, a puffer fish may stop inflating completely. It may return to its normal behavior once it regains energy. 

In a Nutshell 

A puffer fish can deflate by removing the water or air it inhales. It forces the water or air to flow back in a reverse route. Most blowfish can take up to five hours to return to their original size. 

Marine biologists advise scuba divers and puffer fish owners to stop scaring blowfish for entertainment. That’s because the fish can experience fatigue. 

Many puffers may lose their ability to expand when forced to inflate more than usual. 

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