The helpful aquarists guide to fish swimming in circlesYou might have seen your fish swimming in circles and wondered about the reason behind such erratic behavior. A school of fish does swim in circles in the sea. However, when you witness your small collection of fish replicate these actions in an aquarium, you might find yourself stressed.

There is no need to fret as this article can tell you why your fish are swimming in circles and give the insight you need to take the necessary steps to put your beloved pets at ease.

Why Is My Fish Swimming in Circles?

Observing and understanding the swimming patterns of fish can give a pretty good idea about when things are normal and when there is cause for concern.

You see, a school of fish swimming in the sea or ocean does swim in circles. Being part of a large group of fish helps protect from predators, makes feeding easy for spawning purposes, and generally makes it more efficient for swimming.

A fish swimming in circles in an aquarium can indicate many different things. However, fish swimming in circles inside a fish tank isn’t the same thing.

Let’s take an in-depth look at each of these reasons.

– It Might Be A Sign Of Disease

Fish that are unwell will express their discomfort in several ways. If your fish are feeling out of sorts, then you will, in all likelihood, find them swimming in circles.

Additionally, there is an illness known as the whirling disease caused by the parasite called Myxobolus cerebralis. It infects the inner ear and the brain of the fish, causing neurological and balance disruption. And results in fish spinning in circles.

Tropical fish are highly susceptible to ‘swim bladder disease.’ The swim bladder is an inflatable organ that allows fish to control buoyancy. However, when the swim bladder is infected or damaged, fish lose control over their swimming actions and float face up, down, or on their sides. With the swim bladder disease, you will see fish swimming in circles and then dying.

You will need to contact a vet specializing in aquatic life immediately for advice and treatment. The treatment for the disease in fish usually entails over-the-counter medicines and quarantine.

– There Can Be An Infestation Of Parasites

If your fish become infected with parasites, you will probably find your fish swimming erratically in circles. Nonetheless, if you take a closer look, you will notice that your fish will not just be swimming in circles but repeatedly bump or rub against rough objects to get rid of the parasite.

This behavior is also known as flashing, where your fish are rubbing themselves against rugged objects in an attempt to scratch themselves.

The most common parasite found in fish is Ich, similar to fleas in mammals. Another parasite often found in fish in aquariums is gill or skin flukes. These parasites can be seen as tiny white specks or dots on your fish’s scales, and it can be both a harrowing and irritating experience for your fish.

Unfortunately, these bugs are more difficult to spot. However, if you notice excessive visible mucus, fading in the fish’s color, or a change in the appearance of the gills, you should not waste time contacting a vet.

– It Can Be A Territorial Action

The good news is that it’s not all bad news. Fish look like dainty and delicate creatures, but some fish don’t like to have their paths crossed. Fish depicting territorial actions such as angelfish, betta fish, or cichlids need plenty of room to maneuver.

These fish, and many other species like them, swim around in circles marking the perimeters of their territory. And swimming in a circle is a performance to let other fish know that they are not welcome within the circle.

The easiest solution to the problem is to give your fish a lot of tank space and put in plants and ornaments so that there are many hiding spots and room to swim around freely.

– There Can Be Bullying Underway

Yes, fish bully other fish. And, a fish swimming frantically in tank space can be a victim of bullying. When fish are bullied, they show signs of stress. But, fish are also apt at skills to confuse their bullies.

Fish swim furiously around in circles to confuse the attackers. A still object is an easy target, but a constantly moving fish presents a challenge for other fish to aim; however, fish can’t sustain stress for long.

– It Could Be Work-Out Time

Fish swimming in circles doesn’t necessarily have to hint at doom and gloom. As mentioned before, fish in the sea or ocean do swim in a circular motion for a variety of reasons. In addition, yes, your fish isn’t in the ocean or sea anymore, but that doesn’t mean it will forget what is known as muscle memory.

Fish with excessive pent-up energy swim as a form of exercise. Now, fish in the sea have that large area that they can cover to burn up excess energy. However, your fish will adapt to its limited environment and swim in circles to cover the ground it needs to shake off the extra zeal.

Additionally, some fish don’t swim the entire length of the fish tank and prefer swimming in circles to avoid confrontations and possible breakout of fights with other fish.

– Your Fish Like To Play

Yes, playful fish swim in circles, too, and yes, some fish love to play. Tropical fish, in particular, are found to have fun-loving personalities, and they like nothing better than to play.

Fish, like dogs, chase their tails, and it’s nothing short of fun to watch. If you have playful fish and you see no other symptoms, you need not be concerned about your fish’s health. Providing some floating toys such as ping pong balls will keep your pets entertained for hours.

– The Fish Tank Environment Needs To Be Monitored Closely

It would be best if you kept a close eye on your fish’s habitat. Plenty of things happen to the water inside a fish tank, and you need to perform frequent water tests to ensure that the water is safe for your fish.

The pH levels can vary; there can be ammonia build-up, high amounts of nitrates or nitrites, or environmental changes that can cause your fish to swim erratically.

When the water inside an aquarium is not suitable for your fish, you will notice that your fish will demonstrate their displeasure toward you through their behavior and actions.

How To Stop Fish From Swimming in Circles?

How to stop fish from swimming in circles will depend on what’s causing their behavior. For example, when dealing with infections, illnesses, or parasites, getting in touch with a qualified aquatic vet is essential.

The vet will provide your fish with the medical treatment they need to be clear of their health condition. Ceratin natural remedies can be applied to eliminate skin flukes in fish.

Conversely, if you’re dealing with anchor worms, these are a crustacean copepod parasite that embeds into the fish’s skin and has a worm-like tail. The spread of these parasites can be pretty rapid. And it usually occurs when a new fish is introduced into the aquarium without quarantine.

In short, getting in touch with a vet as soon as possible is the best recourse. If your fish are swimming in irregular patterns due to unsuitable tank mates, you might have to consider moving the bullied fish to a new tank.

– Additional Remedies

Other remedies include placing ample plants or decorations inside the fish tank to ensure many hiding spots for the smaller-sized fish being bullied into taking refuge. Or you can remove the offender from the aquarium and place it in another tank.

It would be best if you tried to do some research when you decide to buy your collection of fish to find out which species of fish live harmoniously together.

However, there is always a chance that some fish may revert to aggressive manners due to the new environment, and you ought to take prompt action if you want to prevent any severe injuries in your fish.

Finally, for aquarists suffering from poor water quality, a high-quality filter, and frequent and small water changes can work wonders. It’s also best to have a water testing kit handy.


Fish swimming in circlesYou now have the necessary knowledge to discern why your fish swim in circular motions using the information from the article. But, before you leave, we can recap on the finer points:

  • Fish often swim in a circular motion, but when you see your fish show erratic behavior, you need to investigate the matter.
  • Water tests must be performed regularly to ensure that there is no ammonia build-up, the pH levels are normal, no nitrate build, and no drastic temperature changes the well-being of your fish depends on it.
  • When fish have a disease or are infested by parasites, fish tend to swim in circles.
  • You also need to perform regular water changes to ensure that the water is clean and use a water or air pump to keep the water aerated.
  • If you can’t figure out why your fish are swimming in circular motions and very frantically, then you can enlist the help of a vet who specializes in marine life for a minimal fee.

Understanding fish behavior will help you better care for your fish. If you discover that your fish loves to play when you find them frequently swimming in a circular motion, you can be sure that you will have a great time watching them play.

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