Are fishes animals or not?

Fishes aren’t animals: A seemingly common misperception

According to science, fishes are classed as animals. Find out why some people believe that fishes are not animals and whether it's okay to eat fishes.

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This article is based on scientific evidence, written by experts, and fact-checked by experts.
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The classification of living things into groups isn’t straightforward. As a result, you may be confused about whether fishes are classed as animals, or if they are something else.

Biology uses definitions to group the world into ‘kingdoms’. There’s the animal kingdom as well as separate kingdoms for things like plants, fungi, and bacteria. However, even science textbooks don’t all agree on exactly how many kingdoms there are!

So, is a fish considered an animal? Yes? Or no?

Are fishes considered animals?

According to science, fishes are classed as animals. Fishes belong to one of the six general animal groups which are: mammals, birds, reptiles, amphibians, fishes, and invertebrates. While the flesh of fishes might not be considered as meat, fishes are animals that have brains and can feel pain.

What category of animals are fishes?

fishes are a type of animal known as vertebrates – this means that they have a backbone. ‘fishes’ is a unique grouping of animals – just like mammals, birds, and reptiles.

There are lots of different kinds of fishes, which range in size from the dwarf minnow at around 1 cm to the whale shark which can reach up to 10 meters in length. All fishes live in water and have gills, scales, and fins.

Fishes can be categorized into three main types:

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What defines an animal?

According to biologists, animals are defined by having five common characteristics:

Fishes meet all of the criteria for being animals, just as pigs, parrots, spiders, and humans do. Therefore, it is generally agreed that fishes are animals.

How are fishes different from other animals?

Fishes are very diverse creatures. There are more than 32,000 species of fish, which is more than all of the mammals, birds, reptiles, and amphibians combined.

Sharks, rays, eels, and sea horses are all 100% fishes, whereas whales, dolphins, starfishes, and jellyfishes are not fishes. So what makes fishes different from other animals?

Fishes are unique in that they have a combination of gills and fins and that they live only in the water. While some invertebrates and amphibians have gills, some mammals and amphibians have fins and lots of animals live in water, only fishes have the combination of all three attributes.

Do fishes have brains?

Just like almost every other animal on the planet, fishes have brains. The few creatures that don’t have brains include corals, jellyfishes, sea cucumbers, starfishes, sea urchins, sea sponges, clams, and oysters – but none of these are fishes. They are all invertebrates.

Do fishes feel pain?

It is widely accepted that fishes can and do feel pain. Fishes brains have neurons called nociceptors which detect intense pressure, temperature changes, and caustic chemicals. Fishes produce the same opioids (innate painkillers) as mammals do in response to injury.

The false belief that fishes cannot feel pain causes some people to take part in hobby fishing when they wouldn’t take part in other blood sports like shooting rabbits or deer. If they were aware that fishes feel pain just like rabbits do, perhaps they would think twice.

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Do fishes have feelings?

Because fishes lack facial expressions, it’s sometimes assumed that they are incapable of feeling emotions. However, science is increasingly demonstrating that fishes are sentient and emotional beings.

Just like other animals, fishes respond to painful events with changes in their behavior and physiology. Fishes learn to avoid things that cause them harm, which helps them to survive.

It’s a myth that fishes have short memories. Goldfishes have been shown to remember the exact colors and locations of specific feeding tubes up to a year after exposure.

Fishes may not be capable of experiencing the range of feelings that humans and some non-human animals do, such as anger, joy, worry, amusement, and disgust. But to say that fishes don’t have any feelings would be inaccurate.

Why would someone say a fish is not an animal?

Some people might assume that animals are medium-sized four-legged creatures, as those are the animals that they are most familiar with. They may not know that the animal kingdom spans all sorts of animals, including marine life like fishes.

Another reason why people may think that fishes are not animals is because of the Catholic doctrine which states that Catholics must abstain from eating meat on Fridays, but that they can eat fish.

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This may cause some people to wrongly conclude that…

This type of faulty reasoning is known as a fallacy.

Why isn’t fish considered meat?

When we look at the history of how fishes came to be considered not meat, we can see that this is influenced by both religion and language.

The religious definition of meat

The Catholic Church defines meat as the flesh of warm-blooded animals. Interestingly, this classification comes from religious leaders, rather than biologists.

There is a story that says that, centuries ago, a medieval pope with connections to the fishing industry banned the consumption of meat on Fridays to give his friends’ fishing businesses a boost. While this seems plausible, it isn’t true.

The real reason why some Catholics avoid meat on Fridays stems from the Biblical tales of how Jesus fasted for 40 days and how he died on a Friday. To honor his sacrifice, Christians originally fasted on Fridays, eating only bread. By the Middle Ages, the fast had evolved so that they were eating more things, but still avoiding the tastiest foods – meat, eggs, and dairy. Eventually, people just avoided the meat.

In ancient times, meat was considered a luxury. Eating something as decadent as beef wouldn’t have been seen as an appropriate way to act on a Friday when, according to religious leaders, their focus should be on sacrifice.

The dictionary definition of meat

According to the Cambridge dictionary, ‘meat’ is defined as ‘the flesh of an animal when it is used for food’. By this interpretation, fish would be a type of meat.

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The Merriam-Webster dictionary defines ‘meat’ as ‘animal tissue considered especially for food’. However, it then goes on to specify that meat means ‘flesh of a mammal as opposed to fowl or fishes’.

It seems that even dictionaries cannot agree as to whether fish is a type of meat. Whether you consider fishes to be meat or not, this doesn’t change the fact that fishes are animals. But it does go some way to explain why people may think that they’re not.

Is it okay to eat fish?

The decision to eat fish or not is a personal one. However, those that do choose to eat fishes would be wise to educate themselves to ensure that their decision is made on sound principles.

Many people opt to eat fish because they enjoy the taste and believe that a diet that includes fish is beneficial to their hearts and brain. The NHS recommends that people eat fish as it is a source of vitamins and minerals.

However, it is possible to get these vitamins and minerals from plant sources and there are some downsides to eating fish that cannot be ignored.

Reasons to consider avoiding fishes:

  1. Fishes feel pain when they are caught and killed
  2. Fishing causes the death of other animals such as dolphins, turtles, and birds
  3. Commercial fishing is bad for the environment
  4. Fishes live in polluted waters so their flesh can contain dangerous toxins like mercury

The problem with pollution is that although the NHS recommends eating fish, it also recommends that children under the age of 16 and women who are pregnant, breastfeeding, or may wish to become pregnant in the future should avoid eating fish too often. Some types of fish should be avoided completely because pollutants can stay in women’s bodies and harm their unborn babies even years later.

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Can vegetarians eat fish?

Vegetarians do not eat the flesh of animals. As fishes as animals, vegetarians do not eat fish or seafood. Those who choose to avoid eating all animal flesh except for fish and seafood are known as pescatarians.

Do vegans eat fish?

A vegan diet involves abstaining from eating any animal products. As fishes are animals, vegans do not eat fish.

What do you call a vegan who eats fish?

A person who follows a vegan diet except for fish is known as a “Seagan”. This portmanteau is formed by blending the words ‘seafood’ and ‘vegan’. The “Seagan” diet isn’t new – it mirrors the traditional Japanese way of eating.

Seagan vs Pescatarian

Both “Seagan” and pescatarians avoid animal flesh except seafood. The difference is that “Seagans” also avoid animal products like eggs, dairy, gelatine, and honey, whereas pescatarians will eat these things.

Can vegans have pet fishes?

Whether vegans should have pets and what pets are suitable for vegans is a much-debated topic.

There’s no straightforward answer to whether vegans can and should have pet fishes. Keeping a wild-caught tropical fish in a small fishbowl is quite different from rescuing unwanted pet goldfishes and caring for them in a garden pond.

The bottom line – fishes are animals

Nobody can deny that fishes are animals. While many definitions of ‘meat’ do not extend to include fishes, this does not mean that fishes are not animals. Fishes have brains and can feel pain, just like other animals can.

When deciding whether to consume the flesh of fishes or not, people should be aware of the implications that this may have on their health, the health of their unborn babies, our planet, and the fishes and other animals that are killed as part of the fishing industry.

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Last updated on September 1, 2021, and last reviewed by an expert on August 16, 2021.

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