Can Fish can Swim Backwards?

Fish is a mysterious being and how they work and survive seems to fascinate almost everyone. The fact that they live within the water, a different ecosystem than ours is enough to catch attention. How they breathe, sense danger, find food, everything is done in a perplexing or a different way. As we know fishes swim in the forward direction most of the time. If you think they are only capable of swimming forward, you are mistaken. Some fishes can swim backward. This thought might not have crossed your mind as it is etched in everyone’s mind that fishes only swim forward.

Fishes are capable of swimming backward, but not all of them. Certain species can swim backward. A fish swimming in the opposite direction is a rare occurrence, and if you have witnessed your fishes do it, consider yourself lucky. If you catch your fish swimming backward, it won’t be for long. They usually do it if they are evading danger or are hastily looking for a place to hide.

This question is one that has caught the attention of many aquarists. Seeing a fish swimming in the aquarium and pushing it’s body forward with the force generated by waving its caudal fin may make a person wonder if fishes could do the same thing going backward. The answer to this question is: fishes can swim backward or in a reverse direction.

While it is established that fishes can swim backwards, it is also important to note that they rarely do so. Hence, the probability of seeing a fish swim backwards is extremely low except you are an ardent aquarist. 

Can All Fish Swim Backwards?

Swimming in a backward direction is an ability that is common to most fishes. However, most of them do not display it frequently enough. Hence, it is very possible to have a fish in your aquarium that can swim backwards but never swims that way. 

Actually, only one fish has been actually proven not to swim backwards. Hence, it is safe to hypothesize that “more or less, all fish possess the ability to swim in a backwards manner”. Exhibiting this ability, however, depends on the conditions surrounding the fish. Most of the time, it is the search for food or the hunt for prey that makes most fishes display this attribute. 

The only groups of fish that display this attribute frequently are electric eels.

Mechanism of Fish Swimming Backwards

Swimming backwards is not frequently done by fishes because it requires an entire change of swimming mechanisms. In swimming forward, the caudal fins actively generate all the force needed for the fish to propel itself forward.

However, in swimming backwards, a different set of fins are needed to generate enough propulsion force for motion. The pectoral and anal fins work more in making backward swimming possible in fishes. Like all things done against the normal cause of nature, backward swimming requires a lot of energy. This is why it is done less frequently.

Do Electric Eels Swim Backwards Frequently?

It is interesting to note that electric eels swim forward and backward with the same ease. It is very common for electric eels and rays to swim backwards in order to inspect their environment. Eels and other electric rays generate high-intensity current to kill their preys and predators while low voltage current is required for communication and navigation. They generate electric current to aid their movements in the water and to track their preys. They move around their prey in all directions; forward and backwards. Hence, swimming backwards is quite normal for them.

How Do Electric Eels Swim Backwards Frequently?

Eels have a special mode of movement known as Anguilliform locomotion. This form of movement is specific to eels and during this movement, they move their entire flexible body at the same time.

Their movement is sigmoid (sinuous) or S-shaped and involves their whole body. This anguilliform movement usually uses pectoral and anal fins to move against the flow. 

Why Eels Need To Swim Backwards

Eels and electric rays need to sense their environment. However, while doing this, they must keep their mouths open for their prey. Thus, these fishes find it a necessity to swim in a backward direction.

They frequently release low voltage currents and detect their surroundings. Then, once the prey is selected, they move in the reverse direction. This is for the purpose of positioning their mouths just behind the prey. Once they are in this position, they generate high voltage currents and stun their prey.

Hence, electric eels must always move in the reverse direction to effectively consume their prey, otherwise they will miss their meal.

An Electric Fish That Does Not Swim Backwards

The South American fish, Rhabdolichops troscheli can generate electricity but cannot swim backwards. The reason why it can’t swim backwards is not farfetched. Rhabdolichops troscheli lives in areas with strong currents. They would suffocate if they stopped swimming forward for even a short period of time. 

How Long Can Fish Swim Backwards?

Swimming backward is very difficult and requires skill and experience. Swimming backward for too long can be fatal because fish may die of suffocation. This is because the respiratory system of fish works as the oxygenated water flows in through its mouth and moves out through gills.

The water that flows through the gill is the source of oxygen and it helps in the removal of waste and carbon dioxide. During a backward swim, the movement of water through gills is not adequate and it may lead to hypoxia. This way, fish might suffocate. Hence, swimming backwards can not be done by fishes for too long.

Fishes don’t or cannot swim backward for longer periods. Swimming backward for longer periods is not good for the fish, and they are aware of it. Swimming reverse is not the ideal way for them to swim.

Their gills are built to function in the forward direction. If the fish swims in the backward direction for too long they will suffocate as the gills won’t be able to work properly. As the water is meant to come in through the mouth and drain through the gills. So when moving backwards the opposite will happen and fishes will suffocate.

Not only swimming backward, but the owners must not pull them back as well. Don’t do it, and if you have kids in your home, tell them not to do it as well. Pulling it backward will have the same consequences as swimming backward. They will suffocate and die eventually.

Which fishes can swim backwards?

The master among the fishes that can swim backward is the eel. Eel is by far the best known backward swimmers as they can undulate the fins in their bellies. This makes it very easy for them to catch their prey. Their elongated and flexible body as adds up to the easiness of swimming backward.

The knife fish is also an excellent backward swimmer. They swim backward by undulating their belly fins, similar to eels. Triggerfish are also among the fishes that can swim backward quite well.

Although they cannot do it for too long. The bluegill sunfish can swim backward as well. They adjust their dorsal and anal fin to move and use the pectoral and caudal fins to make their swimming precise.

There are other fishes such as bettas, goldfish, clownfish, etc that can swim backward. Although to witness them swim backward you need to have a keen eye and a bit of luck. They don’t always swim backward like it is their favorite thing to do.

These fishes usually do it if they are evading their danger or during a confrontation with other fishes. But if they are swimming backward frequently it might indicate that they are having issues with their swim bladder.

Which Fish cant swim backward?

The shark is the only known fish that is completely incapable of swimming backward. Sharks are unable to swim backward due to their cartilaginous bones and the inability of their pectoral fins to bend upward.

Their gills and scales, as well as their general structure, hinder their ability to travel backward. Sharks can only swim forwards and they have to change their direction to avoid something. Hard being a shark, isn’t it?

Fishes are always fascinating. The fact that they can swim backward is astounding and shows the extent of things they can do for survival. Although they night not swim peculiarly for long as they can harm themselves if they do so. But even if they swim backward for a short period it looks captivating.

Glance at your aquarium now and then, and you might see your fish swimming backward. If they are swimming backward it also indicates that they are intimidated, and your fishes are not getting along.

Therefore, you can remove the aggressive one and move it to another tank. Remember not to pull your fish backward, as it will suffocate them and make their life miserable for a while.

The Harms of Swimming Backwards.

This is the reason why most fish don’t swim backwards even though they possess the ability. Movement is slow while moving backwards. Also, swimming backwards for too long may be fatal for the fish as they may suffer difficulty in breathing. This is due to the inadequate flow of water through their gills. This could lead to the death of the fish.

The Only Fish That Does Not Possess The Ability To Swim Backwards

Swimming backwards is a common trait in many fishes and may be exhibited based on their environment. However, one fish doesn’t possess this trait regardless of it’s environment. That fish is called the Shark. Sharks can only swim in a forward direction. This is why it is said that the easiest way to kill a shark is to pull it in a reverse direction. The shark will suffocate and die quickly. Sharks have only a limited set of swimming options. They can’t swim backwards. This is because their pectoral fins are rigid and can’t bend in the direction needed to produce enough force to thrust the shark backwards.

Swimming backwards in fishes is not a myth and can be done by most fishes depending on their physical conditions and their environment.