Fish are intelligent animals who lead complex lives that rival those of your dog and other mammals.

Dolphins and whales are accepted without doubt as intelligent creatures, sensitive, aware, conscious: sentient. But what about other aquatic creatures, the myriad species of fish, 27000 in all, which is more than all vertebrate species combined, are they sentient? Approximately three new species of fish are discovered each week! And even more vast are the huge numbers of species of invertebrate creatures such as molluscs - Octopuses, squids, snails, slugs, do they posses sentience? The ocean is a vast habitat teeming with life, astronomical in number and diversity, creatures dwell even in the most inhospitable of environments. 

Here I will focus my attention on fish and Crustaceans particularly lobsters and crabs as it is these creatures who are mostly exploited as food, however in the catching of fish and lobsters many other aquatic animals suffer and die as a consequence and you can read why by clicking here:
Animal Rights: Aquatic Animals. The reason that this article will only focus on fish, lobsters and crabs however does not imply that other aquatic creatures lack sentience, in my opinion most animals are sentient, and in time I will add information as it becomes available concerning the sentience of other aquatic animals, but for now most of the readily accessibly information is limited and would require more  research by me and will take time. 

To begin with lets discuss fish. What are the indicators that fish are sentient.

It is often considered that fish are primitive life forms, however as the oldest vertebrate group of animals they have been evolving for 400 million years, they have had time to evolve complex and diverse behaviours. Because of their amazing diversity fish are said to be the most successful of all vertebrates.

One good indicator of sentience is a creature's ability to express emotion, but how is emotion expressed in fish? How do we know that a fish feels distress or fear, how do we know if he feels pain or joy or experiences pleasure? Another good indicator of sentience is intelligence, are fish intelligent? Many people think not, but research is proving otherwise.

Pain is the most basic indicator of sentience, but do fish experience pain? The excuse of anglers when catching fish with hooks that pierce thier mouths is that this area is numb and they do not feel pain. As you will see later on this is one of the most erroneous misconceptions of all the incorrect ideas many people have concerning fish, it is as unfounded as the notion that cows keep producing milk.

Expressing her concern about the increase in the consumption of fish and the use of them in medical research, Ms.Yue considers that the problem is that most people experience an emotional distance from fish and consequently do not consider them as sentient, as creatures who feel pain or experience emotion. She says;

Lets start with the most popular criterion which many people adhere to as indicative of sentience: intelligence. As before it is important to bear in mind that intelligence or lack thereof does not imply a lack of sentience, but if we can demonstrate that a creature is intelligent it does go a long way towards establishing sentience. But we should perhaps bear in mind that animal intelligence is not comparable to our own, even though when the presence of intelligence is researched in animals it does seem as though we try to prove animals have similar intelligence rather than demonstrate that animals have perhaps a different kind of intelligence. A degree of intelligence of some type does of course demonstrate sentience, but is nonetheless not a prerequisite.

A number of research projects have demonstrated that despite having small brains fish have cognitive abilities in advance of some mammals. These studies also reveal that fish are fast learners, they can retain what they have learned and they can make mental maps. The following is an extract from The Telegraph concerning research into the intelligence of fish:

To finish reading the article:

"If a rock pool begins to dry up these fish leap to an adjacent pool. Obviously, a missed leap might be fatal, and the accuracy must be great in both terms of distance and direction. How do frillfin gobies do this being as they cannot see the adjacent pool? They memorise the topography of the rocks during high tide. Captive fish showed a marked improvement in orientation after an overnight opportunity to swim over the pools during an artificial high tide.  Removing the gobies from their home tide pools for various periods of time before retesting their jumping ability showed that their memory of familiar pools lasted about 40 days. Thanks to these mental capacities, gobies caught in a shallow depression avoid having to make a pure leap of faith."

Fish are communicate with each other:

Research shows fish can use tools, they have log term memories of at least three or four months and live in complex social structures. 

‘Fish and Fisheries’ journal recently featured a report on ‘Learning and Memory in Fish: Why fish are smarter than you think’. The report, which contains contributions from biologists around the world, claims that fish are capable of pursuing Machiavellian strategies of ‘manipulation, punishment and reconciliation’; exhibiting stable ‘cultural’ traditions; and co-operating with each other to inspect predators and catch food.

Fish not only recognise individual shoal mates, but also monitor the social prestige of other fish and track the relationships of other individuals. They also use tools, build complex nests and can even exhibit impressive long-term memories. Report co-author and edition editor Dr Culum Brown, of the Institute of Cell, Animal and Population Biology at the University of Edinburgh, said: “Learning plays a pivotal role in the behavioural development of all vertebrates, and fish are no exception.”

To finish reading this article from Hero. Hero is the official gateway to universities, colleges and research organisations in the UK Machiavellian fish

Fish have the capacity to feel pleasure.

Sentient beings are capable of experiencing pleasure. Most people would not equate fish as creatures with the ability to enjoy themselves and experience pleasure, again another misconception. Here are some examples of the ways that fish experience pleasure.

All animals like to be stroked, cat and dog owners know the pleasure their animals derive from being stroked and indeed the pleasure we derive from stroking them. Fish it seems also enjoy the sensation of being stroked. Contrary to popular belief fish are highly sensitive to touch, equipped with sensory organs they can detect pressure changes in the water and minute electrical fields.

Grooming by such creatures as cleaner shrimp and cleaner fish is likely undertaken for the pleasure of the tactile sensations involved in addition to the benefits of grooming.

The use of cleaning stations, a place where fish and other aquatic animals gather to be cleaned by fish of several species and other creatures, is a widespread phenomenon. The cleaner fish or other creatures nibble parasites such as fish lice, fungal growth, loose skin and other irritations from the skin. 

Yes most certainly fish like to be touched, they have been observed to rub against one another. Fish even enjoy the sensations of touch by humans and fish who are used to divers often allow themselves to be stroked by them. There appears to be no advantage here, such as food or other benefit, other than pleasure from the sensory sensation.

Do fish seek out pleasure, do they play? 

Quite likely the answer is yes. Again in his book pleasurable Kingdom, Jonathan Balcombe writing about fish and their capacity for play describes Zoologist E Meder observations of elephantine fish in an aquarim :

"After witnessing surprising things going on in his aquarium the Zoologist E Meder moved it to his desk so that he could keep a closer eye on his lone elephantine fish. One day to his astonishment, Meder watched the fish balancing a small aquatic snail on his or her nose. (Meder never determined or divulged the fishes' sex). Small nylon balls added to the tank were treated similarly. When these began to accumulate in the filter, Meder suspended one on a string, and the fish would bat balance and retrieve the ball. That this fish was kept alone suggests that the play-like behaviour may have been driven in part by boredom."

Surgeonfish in at a zoo in the USA were observed to gulp in air at the surface of their tank, swim to the bottom release the air and chase the bubbles to the surface. There is admittedly not a lot of evidence that fish play other than anecdotal, but there are numerous indications that they do. Most of us have seen fish repeatedly leaping out of the water, we may conjecturally imply that this is some form of play as it serves no other perceivable purpose. 

Curiosity?

A curious creature is aware is he not, it is his awareness, his consciousness that sparks his curiosity. Curiosity is a sign that a creature is sentient. But are fish curious? Fish are known to investigate unusual objects in their environment. Children paddling in fresh water often experience first hand the curiosity of little fish who nibble at thier legs.

Capacity to feel pain? 

Last but most certainly not least: fish feel pain. As with all animals the most basic indication of sentience is the ability to feel pain and fish like all animals are capable of experiencing pain.

Without sentience there can be no pain, pain is felt, it is experienced by a creature who is aware, the animal has to be aware, conscious in order to feel the painful sensation and to recognise it as painful and thereafter to avoid a recurrence of the painful stimuli. So if we can establish that fish feel pain we are well on the way to validating the concept that fish are sentient.

Every creature feels pain, without pain no creature would survive for very long, pain is a basic survival mechanism. To my mind it is common sense that fish like all animals feel pain. Fish have the ability to feel pain just the way that your cat or dog does or indeed you yourself.

Below is an article of which the angler should take special note before catching a fish on a barbed hook.

Research challenges the myth among anglers that fish can't feel pain from barbed hooks.

by Victoria Braithwaite

"Every year, sportsmen around the world drag millions of fish to shore on barbed hooks. It's something people have always done, and with little enough conscience. Fish are … well, fish. They're not dogs, who yelp when you accidentally step on their feet. Fish don't cry out or look sad or respond in a particularly recognizable way. So we feel free to treat them in a way that we would not treat mammals or even birds.

But is there really any biological justification for exempting fish from the standards nowadays accorded to so-called higher animals? Do we really know whether fish feel pain or whether they suffer — or whether, in fact, our gut sense that they are dumb, unfeeling animals is accurate?

Determining whether any type of animal really suffers is difficult. A good starting place might be to consider how people feel pain. When a sharp object pierces the human body, specialized nerve endings called nociceptors alert us to the damage. Incredibly, no one ever seems to have asked before whether fish have nociceptors around their mouths. My colleagues and I in Edinburgh, Scotland, recently looked in trout and found that they do. If you look at thin sections of the trigeminal nerve, the main nerve for the face for all vertebrates, fish have the same two types of nociceptors that we do — A-delta and C fibers. So they do have the necessary sensory wiring to detect pain.

And the wiring works. We stimulated the nociceptors by injecting diluted vinegar or bee venom just under the skin of the trout. If you've ever felt the nip of vinegar on an open cut or the sting of a bee, you will recognize these feelings as painful. Well, fish find these naturally irritating chemicals unpleasant too. Their gills beat faster, and they rub the affected area on the walls of their tank, lose interest in food and have problems making decisions."

Finish reading the complete article

That Fish You Caught Was in Pain

In my view there is nothing that can outweigh the cost of suffering to another creature, most certainly not financial or recreational, both of which are very minor considerations. There are numerous out door pleasurable pursuits which cause harm to no creature, for instance bird watching and walking. There is nothing more exhilarating than walking in natural surroundings and observing nature and the great variety of life both on land and in the water, surely to experience nature and her creatures as live animate beings, must be a more satisfying experience, rather than fishing - viewing the demise of another living being after struggling for his last gasp of air, in pain, on the end of an anglers barbed hook!

For scientific evidence read about recent research by scientists from the Roslin Institute and the University of Edinburgh:

BBC NEWS | Science/Nature | Fish do feel pain, scientists say

Often cruelty to fish is not considered due to the misconception that fish do not feel pain, that they are not sentient, and most bizarre of all, that they are not animals despite the fact that most people have had at least basic biology taught to them at school. Trying to change the way people think about farmed land animals is difficult enough but when it comes to fish the task is even more problematic. Fish and other aquatic creatures need to be treated with the same consideration as other sentient beings such as your dog or cat or your budgie. Birds of course and in particular poultry are often considered in the light of similar misconceptions.

Read more about the common misconceptions concerning fish and the abuse that they sufferer as the are dragged from their watery environment.

Animal Rights: Aquatic Animals

Please note: I have included aquatic animals in discussions of the welfare and sentience of farm animals, although for the most part with a few exceptions such as trout and salmon they are not farmed in the literal sense, nonetheless they are controlled and exploited for food therefore for ease of expression I will refer to fish and other aquatic creatures as farm animals.

Now please read about sentience in crustaceans

Sentience in crustaceans

References and Links :

Internal

Animal Rights: Lobsters

Sentience in crustaceans

External