Do fish know they are in a tank?

Table of Contents

Fishes are, of course, great pets that melt the strings of our hearts. With their simple style of living and seamless swimming movements, They bring that soothing peace after a long day at work. The rate of people owning a fish pet has grown over the years, with more households embracing the idea of having a tank. Domestic owners of these pets normally rear them in tanks and provide them with the resources they need for healthy living.

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Pet fishes in tanks have been claimed to exhibit what some owners describe as intelligence and emotions similar to empathy. These claims, despite not verified, have triggered owners to ask the question if fishes possess the intellectual capacity to understand they are in a tank.

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Fishes in tanks have shown great adaptability with their surroundings and have even flourished in them, but does this imply they understand that this surrounding isn’t a natural habitat or home? From research, there is no scientific data that suggests fishes have the capacity to carry out cognitive reasoning that is needed to understand that they are in a tank. Like most species, they move, live, and thrive on instincts with no understanding of the past or realization of the next moment and, therefore, cannot detect they are in a tank.

However, not understanding they live in a tank doesn’t mean they are oblivious to it. Fishes learn the tank, adapt to the surroundings, and see it as their home. They just can’t tell that it is a tank.

Do fish know they are in a tank
Do fish know they are in a tank

Do fish get bored in a tank?

Fishes have always been a unique set of species in terms of their surroundings. Their growth, activities, and colour can be affected by their surroundings. Their brains and behaviours can be conditioned by the things they do every day, and this is also true for fishes bred in tanks. According to research, young fishes reared in a small, featureless, dull tank end up with a smaller cerebellum than those groomed in a colourful tank with leaves and plants to engage with. Also, fishes reared in a more active tank are better at catching prey and better at recovering from stress.

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Does this mean that a tank can trigger boredom in a fish? Is it even possible for a fish to get bored? Clearly, from the research stated above, active tanks give fishes tasks to engage in daily while the other tank causes inactiveness in fish movement leading to them developing a small cerebellum – the part of the brain responsible for movement.

However, despite the two distinct behaviours that can be influenced by a fish due to its tank, it is still difficult to state that the lack of movement in the second tank will eventually lead to boredom. Boredom is an emotional state and, in this case, can be caused by insufficient movement—a situation apparent in the first tank due to its size. Fishes, however, do not possess emotion and have never, in any case, shown discomfort because of a small tank unless it happens to be overcrowded. Lack of movement in a small tank may cause a lot of negative effects in fishes, but research indicates that boredom is not included.  Therefore fish do not get bored in a tank.

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What Do Fish See From Inside The Tank?

Fish owners have always wondered what their pets see when inside their tank. Do they get a view of the room, or do they see their reflection staring back at them? Actually, fish can either see their reflection or have a view of the room they are stationed in, depending on the angle and the type of tank.

Fishes at an angle determined by the refraction indices of the glass, air, and water can have a view of their external surroundings. This angle forms a circle that moves along with them as they swim. This circle gives them a circular view of the room their tank is stationed in. It is even possible for them to recognize things always stationed at a particular part of the room over time.

It is also possible for fishes to actually see their reflection from inside the tank. Typically, when this happens, they burst into a flurry of activity as they try to chase their reflection. Owners normally have this experience when mist or algae is cleaned from the tank.

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Do Fish Know Their Owners?

There is some confirmation that indicates that fish can form a bond and connect with their owners. Before now, fishes were thought of as species with little ability and extremely short memory spans. Recently, however, science has shown that fish possess instinctive intelligence and can establish a significant bond with people good to them.                                                    

As humans, we tend to express reasonable affection for pets that can recognize their owners, and this has led to a lot of tank owners wondering if their fish can be as smart as dogs and cats and can recognize them. Fishes are not as smart as dogs, but recent studies have shown that they can retain their owners’ pictorial memory. Before research proved otherwise, there was a popular claim about Goldfish having a three-second memory, a statement used in describing fish’s inability to recognize their owners. Dr. Cait Newport, an animal psychologist, carried out research to answer the question on fish ability to recognize their owners in her study titled Discernation of human faces by Archerfish. Her research was to find out if a fish could remember one particular face. Each Archerfish in the study was taught to point out a photo of a human face by spitting water at the photo. Teaching each fish was relatively easy, with most fishes completing their training in a few days.


With 44 pictures of human faces set up, the fishes spat at the correct face with an accuracy of 81 percent. Following this research, other research has been conducted and arrived at the same conclusion.    

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Do Fish Get Lonely In A Tank? 

Fishes, unlike most animals, have complex characteristics due to their vast species. What may work for one can have the opposite effect on another. There is no specific behaviour for fishes, and that also cuts into whether they can get lonely. The study of loneliness cannot be generalized for fishes as some are extremely social and thrive in groups while others are highly territorial and should be best left alone.

The Betta fish, for example, are highly territorial and do not express any sign of loneliness when left to a tank. It may be okay to keep four or six Betta females together in a tank, forming a female sorority tank. They would live together comfortably but would still need their personal space, so enough aquarium decorations, which would serve as a hiding place, would be good for them. On the other hand, keeping two males together would be fatal as it would lead to unending fights that would leave one or both dead.


There are fishes that enjoy being in groups. The Goldfish, for example, prefer to be in groups as it lets them socialize, play, and have fun. If a goldfish is left alone, especially after being first joined to a group, it may begin to develop unhealthy symptoms like refusing to eat and stress. This could eventually lead to its death if left unchecked. In conclusion, some fish species feel lonely when they are all by themselves in a tank which could be disastrous to their health, while others are better off alone.

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Is It Cruel To Keep Fish In A Tank?

In the 21st-century, animal cruelty by humans is a touchy and sensitive topic, with a lot of animal rights groups whose aim and purpose is to enlighten the public on why they should be more accommodating to animals.  Since the establishment of anti-animal cruelty movements, a lot of people have been able to adjust their views on animals and have become more encompassing and tolerant towards them. 

Typically, when animal cruelty is discussed, both wild and domestic animals are taken into consideration. Fishes with their different species cut across as domestic and non-domestic, and just like other animals, they have also been subjected to animal cruelty. There have been lots of cases about fish cruelty, with concerns about them growing.

Among the concerns raised on fish cruelty, one of the most animated discussions is about them being kept in tanks. A lot of activists and owners have been divided on this issue on whether it is cruel to keep a fish in a tank. The answer to this question is quite complex and highly subjective. Most people involved in this discussion are barely informed on fish nature and end up making ill-informed statements. Most fish kept in tanks are domestically bred species, and just like most domestic animals or pets, they cannot fend for themselves. To care for them, they have to be placed in a safe environment. A tank can serve as a safe haven for them and, as such, cannot be considered as cruel. However, it will become cruel if incompatible or territorial fishes are stuck together, as this will lead to fish stress. Also, overcrowding them in a small tank can be unhealthy for the fish and seen as cruel. Another form of fish cruelty would be to keep a wild fish in a tank, as this comes with a lot of negative effects. 

Do Fish Know They Are In Water?

As humans, our brains are programmed to carry out high and complicated tasks. We also have the ability to carry out cognitive reasoning and can get a grasp of our reasoning. We can learn new and complicated things and even ignore things we have learned when they are no longer helpful. Humans can reflect on the past, try to fix the present, and plan for the future. The ability to do these things makes us more sophisticated and more advanced than other creatures.

In general, other mammals and animals do not have the ability for cognitive reasoning and so do not have a deep grasp of occurrences and situations around them. This implies that fishes do not know they are inside water, just like other land animals do not know they are on land. There have been reports of fishes that died when trying to cross land water barriers during migration; A situation resulting from their inability to tell the difference between their natural habitat and land. Similar occurrences have also been reported for big fishes and other water mammals such as sharks and whales. There have been several reports of whales and sharks finding themselves at water shores and beaches, with humans having to come to their rescue and help them back into the water.

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Why Are Round Fish Tanks Bad?

When home fish breeders hear of a round tank, what comes to mind is a fishbowl. There have been a lot of claims of round fish tanks being bad for fishes, with condemnations soaring after the discovery that the round classic half-gallon goldfish bowl causes ammonium poisoning. The problems of round fish tanks are more noticeable with the smaller ones. Despite having a high chance of poisoning fishes, these sets of tanks also distort their view, leading to stress.

The problem with round tanks is not because they are round but because most of them are small and will end up killing the fish in the long run. However, big round tanks do not have any of the problems that come with small tanks as they can accommodate more water levels and have only minute view distortion if any at all. Some fishes prefer to swim on a horizontal plane, and it is, therefore, cautionary to keep them away from round tanks entirely to avoid them reacting negatively to it. 

The issues of hiding spaces can also be an issue for circular tanks as it may be more difficult to plant hideouts in them than in rectangular tanks.

How Long Do Fish Live In A Tank?

Knowing how long fishes live in tanks will be dependent on species as they all have different life spans. Unlike humans that, if subjected to the same conditions, would have a close lifespan, fishes highly differ in this regard. We shall consider some popular fishes kept in tanks to explain how their life span differs. The Killifish has one of the shortest life spans, living for about a year or two. Betas follow closely living for about two years on average. There have been rare cases of them living for five years or even more, but this is an outlier and not the normal cycle. The Siamese fighting fish lives in an aquarium for three to five years, while livebearing fish like swordtails, mollies, and platys normally live less than five years. Fishes with a Longer life span are the Goldfish, with a healthy one living for up to a quarter-century, making them one of the longest surviving fish reared in tanks. The Goldfish, however, do not live more than a few years in most home tanks, making them a perfect illustration of how poor habitat and maintenance can affect the lifespan of an aquarium fish. Other fishes that live for a very long time are the weather loach and the clown loach, which live up to 10-15 years.        

Benefits Of Having A Pet Fish?                                     

Fish tanks are virtually everywhere. In hospitals, restaurants, corporate industry, tour sites, they are simply becoming a not do without. Several homes all over the world have made it a part of their lives. The reason for this vast acceptance is as a result of fish angelic and calm behaviours. Studies show that they reduce anxiety, stress, blood pressure, lower the heart rate, and help calm the nerves. Aquarium owners all around the world agree that having a fish as a pet holds numerous benefits. They find owning tanks and fishes a fulfilling and noble hobby. 

Research also shows that watching fish in an Aquarium helps people feel better. The act of watching an aquarium helps pass a relaxing feeling that could calm stress and help one sleep better. Studies have shown that Alzheimer’s patients who spend more time around the Aquarium are more relaxed and less aggressive. 

Fishes, just like other pets, can also help lonely people become ehappier and more content. They have also been associated with helping trigger increased productivity in owners.

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Aquariums in homes help to calm kids who need help in regulating their tough emotions, like children with ADHD. The biorb fish tank was designed to be appealing and safe for children with autism as it helps reduce their anxiety and potentially improve their speech. Tanks can also motivate kids to carry out their own research projects and widen their knowledge. In conclusion, owning a tank can help you lead a happier and healthy life.

Hazel Buckley
Hazel Buckley

About Hazel Buckley
Hazel is an animal enthusiast and educator who grew up on a farm which her parents owned in Ingogo, KwaZulu-Natal, South Africa.  The farm was situated right under the Majuba Mountains - the site where the Anglo-Boer War was fought. 

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