Can Fish Swim Backwards? Locomotion in Fishes:

When we take a look at a fish swimming calmly in an aquarium with its caudal fins waving and pushing its whole body forward with that force generated. We often wonder can fish swim backwards.

This question has often caught the attention of many fishkeepers making them take a closer look at their aquarium fish. The answer is Yes, most of the fishes can swim in a backward or reverse direction.

Although reverse swimming is not frequently seen if you are an ardent aquarist, you might have already witnessed it somewhere.

Today we will discuss the mechanism of reverse swimming and other commonly seen patterns of swimming in fish.

Can All Fish Swim in Reverse?

Swimming in a backward direction is a property common to many fishes but most of them don’t display it quite often. You might have a fish at home that can swim in reverse, but your fish might have never displayed this feat.

More or less all fishes can swim in a backward direction depending upon presenting conditions. Most of the time this property is displayed in search of food or prey while moving against the flow of water or in case fishes are inspecting their surroundings.

Although, this ability is commonly seen in my species still it is frequently seen in electric eels and other fishes that can generate electric current.

How Can a Fish Swim in Backward Direction?

Reverse swimming is not commonly displayed as it requires a total shift in the swimming mechanism. In forwarding swimming the caudal fins are mostly active, and they produce all the force necessary for forwarding swimming. They flex their bodies to and fro in a consistent manner.

When it comes to swimming in a backward direction a whole different set of fins are required. While swimming in reverse pectoral fins and anal fins move flawlessly and generate enough thrust to move in the opposite direction.

Backward swimming requires lots of energy and strength, therefore it is not used frequently.

Why Reverse Swimming Is a Common Property in Electric Rays?

An interesting fact about electric eels and other electric rays is that they can swim in forward and backward directions with the same ease. Backward swimming is very common in electric rays as it helps them inspect their environment.

Eels and other electric rays generate high-intensity current to kill their preys and predators, whereas low voltage current is required for communication and navigation.

They move around the prey in all directions and generate low voltage currents and detect their prey. This is the way all the electric rays and eels approach their prey and thus, swimming in both forward and backward directions is a normality for them.

How Eels Swim Backward?

Eels have a unique mode of locomotion called “Anguilliform locomotion”. This type 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 it involves their whole body. This movement usually uses pectoral and anal fins to move against the flow.

Why Eels and Other Fishes Need to Swim Backward?

Eels and electric rays need to sense their environment while keeping their mouths open for their prey, thus these fishes need to swim in a backward direction.

They usually release low voltage currents and detect their surroundings, then once the prey is selected, they move in reverse, so their mouth is just behind the prey. Once they are in position, they generate high voltage currents and stun their prey.

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

Is There an Electric Fish That Can’t Swim in Reverse Direction?

Well, as we just said that all the electric rays and eels possess the quality to swim backward, there is just one exception. The South American fish, “Rhabdolichops troscheli” is one of the species that are capable of generating electric charges but is unable to move in the backward direction.

The reason why Rhabdolichops can’t swim in the backward direction is that they inhabit areas with strong currents, and they would suffocate if they stopped swimming in the forward direction for even a short time.

How Long a Fish Can Swim in Backward Direction?

The main concern is whether a fish can swim backward or not and it’s quite clear now that most of the fishes can swim in reverse. Now the question is how long a fish can keep swimming backward.

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

This water 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 appropriate and it can lead to hypoxia. This way fish might suffocate, thus, swimming in reverse can’t take place for too long.

What Are the Harms in Swimming Backward?

Although most of the fish species possess the ability to reverse swimming then why it’s not commonly shown by fishes?

The reason is that backward swimming requires energy leading to making fishes swim slowly and they can’t keep up the pace.

Furthermore, reverse swimming can lead to the death of fish if kept on for too long. They may suffer difficulty in moving the water in and breathing. This ultimately leads to suffocation and death.

Is There a Fish That Can Only Swim Forward?

Although, backward swimming is a trait common to many fishes and it’s best adapted to their environment. Still, there is one fish that can’t ever display reverse swimming, that is “Sharks”.

Sharks are magnificent creatures that exhibit many traits, but they can’t swim in reverse. The phenomenon of pulling back sharks and killing them is based on the fact that sharks can’t survive the backward swim, so they suffocate and die in that trap.

Why Sharks Have Movement Limited to forwarding Direction?

As it’s been already said that sharks can’t swim in reverse but what is stopping them from doing that.

• Sharks have a limited set of movements; they can’t swim backward, and they can’t even stop in case of an obstacle.
• Their pectoral fins (those involved in the backward swim) can’t bend in the desired direction to produce enough thrust to move backward.
• Furthermore, breathing is greatly hindered while swimming backward leading to the death of sharks through suffocation.
• Sharks can move into depths of water and come back up in no time, thus, using gravity to assist their movement.

Are There Any Other Forms of Swimming Seen in Fishes?

Apart from regular swimming in the forward direction with force generated from caudal fins, fishes can express many different types of locomotion.

Following are commonly seen categories of locomotion in underwater creatures.

1. Anguilliform locomotion:

Eel-like sinuous movement of the whole body, flexible body moves to form S-shaped pattern.

Seen in eels and other electric rays.

• Carangiform locomotion:

The movement is supported by the rear end of the body, generating the required force, and pushing the whole body in the forward direction.

Seen in fishes with fusiform body shapes such as jacks, rays, and pompanos with the rapidly oscillating tail end.

• Sub-carangiform locomotion:

A sub-type of carangiform movement, with increased speed, amplitude, and frequency of oscillation. As a type of carangiform movement, the posterior end of the body supports this movement.

Seen commonly in trouts.

• Rajiform locomotion:

The large force is delivered by pectoral fins in the vertical direction. The undulating pattern seen in rays and skates is an example of rajiform locomotion.

• Gymnotiform locomotion:

Waves formed from the thrust vertically created by anal fins.

American knife fish have long bodies, and they exhibit this form of locomotion.

Which Underwater Creature Can Swim in Vertical Direction?

Apart from forward and backward swimming, some groups of fish also display vertical (up and down) swimming. One of the famous underwater creatures that are commonly seen swimming in the vertical direction is “Seahorses”.

Apart from seahorses, shrimps, tuna, Arowana, and razor fishes are also seen swimming peacefully in the vertical direction.

How To Treat a Fish Swimming in Circles Constantly?

If you are a fish keeper, you might have seen your goldfish swimming constantly in circles and not breaking the cycle.

Mostly this mode of swimming indicates that your fish suffering from “Ammonia Poisoning”. This poisoning could result from the rapid buildup of nitrates and nitrites in the aquarium.

Treatment:

Conclusion- Can Fish Swim in Reverse:

Fishes are intelligent creatures and exhibit many impressive traits. One of such traits is their ability to swim in the backward direction.

Yes, fishes can swim in reverse, and they exhibit this property in times of need such as hunting or inspecting their surroundings. Fishes can also show a variety of locomotion based on their habitat and their body types.

Moreover, if your fish is swimming erratically it also indicates several underlying problems. We will discuss these erratic movements and their reasons in detail later.

Till then best of luck with your fish!!!