Do Fish Have A Heart?

Do fish have a heart like humans? Yes, indeed. Every fish has a heart. Fish have a 2-chambered heart. It has an atrium and ventricle. Blood from the body then enters through the ventricle and is then pumped into the gills.

Gas exchange occurs in the gills. It is used to get oxygen and rid the body of carbon dioxide. The gas then travels throughout the body to the heart.

Humans (all mammals) have both a 4-chambered heart and a complex, more efficient circulatory system. This is what makes us different than fish.

The fish heart is a two-compartment unit. It consists of the ventricle and atrium. This helps with blood circulation and blood pumping throughout the body. Although the heart of a fish isn’t as robust as a human one, it is capable of processing venous fluid.

Do Fish Have a Heart?

Fishes have a single circulatory system. Blood flows from the heart to the gills, then the rest of the body.

The heart is located slightly behind the gills. Although there are four chambers in the typical fish heart, blood flows through them all sequentially, unlike mammals.

Fish also have a heart, just like any other species. The heart of a fish is the most important part of its anatomy and serves as its primary source of life.

A fish’s heart’s workability is very different from that of reptiles, amphibians, or mammals. One atrium is the part of the fish’s heart that receives blood from its whole body.

A ventricle is located in the heart of the fish, and it pumps blood to its gills. This facilitates gill circulation.

You may not be aware that fish blood is sometimes considered to be impure. Why? Why? Because a fish’s heart only has one exit and entry compartment. This helps in the mixing of oxygenated and deoxygenated blood in the fish bodies. This makes them cold-blooded.

The fish’s circulatory system is closed. Fish have a simple circulatory system, which consists of one circuit.

The blood is pumped through the capillary in fish’s gills to their capillary. This functional system of the fish heart is also known as the single-cycle circulation.

How Many Chambers Does a Fish Heart Have?

The fish’s heart is often referred to as a two-chambered organ. There are many theories.

The fish heart is primarily a 2-chambered structure, according to your school biology textbook. The shape of the fish’s heart is different. It has separate entrance and exit sections. This makes it either a three-chambered or a four-chambered.

The ventricle and atrium of the fish heart are sometimes called “true rooms,” while the rest are known as “accessory Chambers”.

Here are the four compartments that are arranged serially in a fish heart.

  • Sinus Venosus: This is the heart of a fish’s body. The sinus venosus is a thin-walled sac that holds cardiac muscle. It draws deoxygenated blood from the incoming cardinal or hepatic veins.
  • Atrium: A thick-walled muscular chamber, the atrium of a fish heart sends blood to its ventricle for additional functions.
  • Ventricle: Another prominent chamber in a fish’s heart is the ventricle. It is a muscular, thick-walled chamber that pumps blood into the fourth compartment, which is the outflow tract. The ventricle’s appearance can change depending on the size of the fish. It can appear sac-like or can take on a triangular or pyramidal shape.

Outflow tract: This tract runs to the ventral arteriosus and includes conus arteriosus (or tubular bulbus arteriosus) or both.

Connective tissues make up the ostial valves in a fish’s heart. They prevent blood from returning to the chambers. This valve closes during ventricular contraction.

These four compartments of the fish heart are not in a straight line in an adult fish’s body. It forms an S-shape, with the last two compartments above the first two. This completes their circulatory system.

Why Do Fish Have a Two-Chambered Heart?

Fish have a low metabolic rate and do not require rapid oxygen delivery to their tissues. Their blood does not become repressurized once it has passed through their gills.

Birds and mammals have high metabolic rates and oxygen demands. Therefore, after blood has passed through their lungs, it is returned to another set of chambers in the heart to be repressurized to allow it to flow faster to other tissues.

How Do You Identify a Fish Heart?

It is easy to identify a fish’s heart. One circuit is the circulatory system of fish. Their blood flows from the heart to their gills and then to the rest.

The fish’s heart can be found just below their gills. It is a dark red color with a triangular shape.

Fish Heart Anatomy

The branchial heart is the name given to the heart of fish. The heart’s primary function is to pump blood through the ventral organ into the gills. The fish’s heart then drives the blood to the somatic vessels.

The fish’s systemic and branchial vascular beds are in a series.

Fish heart anatomy usually includes the four chambers listed above: sinus venosus and ventricle, atrium, conus, and bulbus arteriosus.

Some people think of the ventricles and atrium as chambers for a fish’s heart. Others consider conus arteriosus and sinus venosus chambers.

There are some misconceptions about conus arteriosus and bulbus archirosus in fish. The conus arteriosus is the fourth chamber in the heart of elasmobranchs.

The bulbus arteriosus is a fourth chamber that acts as a ventral aorta in teleosts.

However, regardless of fish type, the heart performance of a fish’s heart is dependent on its heart rate and stroke volume.

The ventricle of a fish’s heart pumps blood to all parts of the body at every heartbeat. The stroke volume is the volume of blood pumped out, and the time between heartbeats is called the heart rate.

Aneural factors such as cardiac filling or circulatory substances control the heart rate of fish. The heart rate is also affected by nerves that run through the muscle and the cardiac pacemaker.

The stiffness of the fish atrium and the adjacent tissues create suction that fills it.

The ventricular contraction in systole aids in the process of venous blood returning to the atrium. This is what causes a drop in intrapericardial pressure.

This pressure is transmitted through the atrium’s thin wall, creating an inspirational effect.

Do Fish Have Heart Attacks?

Fish have heart problems, just like humans. Most fish have the same heart problems as humans. Fish can have heart problems from environmental stress or diet.

Fish have shorter lives than humans so they are more likely to develop heart disease later in life.

Fish with heart problems aren’t usually considered to be more serious than other animals. However, they could have a heart attack in the most unfavorable conditions.

Do Jellyfish Have Hearts?

Although jellyfish are called “fish”, their anatomy is different from regular vertebrate fish.

Jellyfish hearts are not like fish. Jellyfish are a simple species of critter that lack a brain, blood, or heart. Jellyfish usually have three layers that help them do their basic activities.

Their skin absorbs oxygen directly from the water and then processes it. Jellyfish don’t have blood so there is no need to pump it.

Which Fish is Good for Your Heart?

Fish is a good source of protein and has many health benefits. Fish is a healthy and delicious alternative to red meat.

Fish is rich in omega-3 fatty acids and other vitamins. These are very beneficial for many heart conditions and long-term heart health. Not all fish are good for your heart.

Catfish, pollock, and salmon are all good choices. These fish are great for your heart health and should be included in your daily meals.


How Many Hearts Do Fish Have?

Two is the correct answer. Two chambers make up the heart of the fish: the Atrium, and the Ventricle.

What Is The Purpose of a Fish’s Heart?

The heart of fish only has one ventricle and one atrium. The oxygen-depleted blood from the body returns to the atrium and then the ventricle. It is then pumped out of the body to the gills, where it is oxygenated.

Can You Eat Fish Heart?

Fish hearts make a simple and enjoyable culinary organ. Fish hearts taste best when they are freshest.

Do Sharks Have Hearts?

The heart of a shark is a small, two-chambered S-shaped tube that has two chambers. The blood flows from the heart into the gills, then onto the body tissues.

What Does The Heart of a Fish Look Like?

The fish’s heart is dark red in color and has a small triangular shape.

What is The Fish That Reproduces Its Own Heart?

Scientists have identified some genes in Zebrafish that will allow it to regenerate its heart.

How Do Jellyfish Live Without a Heart?

They only have two tissue layers (diploblastic), so all their cells are within close proximity to water for gas exchange or waste removal. The material between the tissue layers can still allow for the transfer of nutrients from food. They don’t need a heart and have been successful for millions of years with one.


Do fish have a heart? The fish heart, which is their source of life, is one of the most important components of fish anatomy. The fish heart participates in blood circulation throughout the body, just like the human heart.

Although the fish heart may not be as efficient as the human one, it still has its unique traits and functions. A fish heart is unique because it works with only two chambers.

If you have a cute fish tank, ensure that you give them plenty of food to support their heart health and happy, healthy lives.


Dibyajyoti Bordoloi is the creator and author of, a third-generation experienced fish keeper and owner of a successful pet breeding farm. He is also a member of the Center for Wildlife Rehabilitation And Conservation (Assam), the Marine Aquarium Societies of North East India, and the Kaziranga Nature Conservancy of Assam.