Estimated read time: 6 minutes.
Pain is a complex concept. Science cannot truly prove that fish, animals or even humans can feel pain – but you know it exists, as you feel it, and you understand that others must feel it too, either because they express or because you observe it through language, other communication sounds and behaviors.
We know when our friend or our dog is in pain, as they will show us. But because fish are less able to express feelings, and we are unlikely to be underwater where we can see it, for too long, they have been left out of the conversation around animal welfare. And, if we are honest, we may have decided for our personal gain, that they cannot experience suffering. This is simply not true however, and science is catching up and showing that fish can in fact feel pain, suffer and express emotions on a complex level.
Do Fish Feel Pain When They Suffocate?
Even according to pro-fishing organizations, asphyxiation as a method of slaughter is considered inhumane. Yet this barbaric practice continues in factory fish farms and at sea. We would argue that it is more than just inhumane and it only takes one experience of seeing fish being asphyxiated to tell you so.
In many factory fish farms, hundreds of live fish are piled into small tanks filled with ice and left to suffocate. There they slowly die as the oxygen depletes from the ice water and research shows that this process elevates cortisol, the major stress hormone in fish. The fish will struggle and try to escape, only to land on the floor of the farm and either be crushed or left to die there instead.
Do Fish Feel Pain When Hooked?
Studies show that fish possess the necessary receptors to process pain and in rainbow trout, 22 different receptors are present around the mouth, eyes and jaw. So with that information, it would be very strange to conclude that fish do not feel pain when hooked. We may not understand whether they feel pain in the same way as humans or mammals, but that does not at all mean their pain is any less relevant to them.
Do Fish Suffer When They Are Dying?
When observing the behavior of fish who are dying in factory farms and on trawlers, it is safe to say that these fish suffer when they die. Particularly when they are left to suffocate over a prolonged period.
How Do Fish Feel Pain?
Fish possess the neurons known as nociceptors, which detect potential harm such as alien substances in the body. They also produce the same opioids or natural painkillers that mammals do, when under duress. Overall, the biology of their nociceptive system is strikingly similar to that of mammals. Yet we clearly accept that mammals can feel pain, and do not afford the same respect to fish.
So the evidence shows that fish are able to feel some kind of pain, as they possess the necessary biological tools to process and feel painful stimulations. It may not be possible to fully understand exactly what kind of pain they feel and how that compares to the pain felt by humans – but does it really matter?
Peripheral Nervous System
It is clear that fish possess a peripheral network of nerves that connect muscles and sensory organs to the central nervous system. So it is safe to assume that fish have the sensory capacity to experience feelings from all over their body, and pain is extremely likely to be included in this.
More and more research is appearing to show that fish possess the necessary receptors to feel pain. One study discovered that the majority of crabs would give up their preferred hiding place, opting for a different one after being administered multiple electric shocks.
Fish possess nerves that connect their muscles and organs with their brain and spinal cord, in order to process incoming feeling and stimulation, just as we do. It is then naive to assume that fish have no capacity to feel some kind of pain.
Central Nervous System
The majority of fish have a spinal cord and a brain, which is connected to the rest of their body by a peripheral system of nerves and receptors, just like humans. This system is designed to process incoming stimuli, including pain.
Most complex and evolved life forms need a brain and nervous system to control the complex array of actions required to survive. Fish possess both. It is highly unlikely that they would have survived for millions of years as a species, if they were not able to experience pain and learn to avoid it.
Scientific Evidence That Fish Feel Pain
There are two forms of evidence that fish feel some kind of pain. Firstly, there is the biological and neurological evidence i.e. the presence of receptors, nerves and opioids. Secondly there is behavioral evidence, where fish’ behaviors are observed when presented with potentially harmful stimuli or are put under duress. Evidence in both forms suggest fish do feel pain.
Opioid System And Effects Of Analgesics
Opioids are the natural chemical painkillers produced in our bodies when we encounter pain. The same system is present in most mammals. The opioid system in fish is strikingly similar to that of mammals, so much so that fish are often used in testing for addiction and withdrawal. Yet we still do not recognize that they could feel pain similar to ours.
Studies on zebrafish have shown clear behavior changes when exposed to potentially harmful stimuli. The same studies also show that when the fish are administered with analgesics (pain relief such as morphine, aspirin or lidocaine), these behavior changes are fully prevented.
Many studies have evidenced the behavioral changes in fish when they encounter potentially harmful stimuli.
Studies on many species including rainbow trout and zebrafish have shown that their behaviors changed dramatically when they received an injection of noxious chemicals to their lips. Rainbow trout displayed protective responses like rocking from side to side on their pectoral fins and rubbing their lips in the gravel. The administration of morphine to the rainbow trout greatly reduced the appearance of these protective responses.
Is Fishing Cruel?
We think so. At a basic level, we like to apply their experience to ours. We can safely say it would be cruel to push a hook through our cheek and to be dragged out of our house, so why is it any different for another species that shares our planet with us?
Should We Care How Fish Feel?
Fish have been honing their skills through evolution for hundreds of millions of years, much longer than us. Research shows various fish species have developed long term memory, interspecies co-operations, social bonding, parenting skills and even tool use. These far outweigh experiences as simple as pain and fear.
Based on the evidence, it seems we would gain a huge amount from caring about how fish feel. Even if we don’t know much about how fish feel, does that give us the right to kill them in their millions, just for a meal we could quite easily replace for something else? We think not.
So there is plenty of scientific evidence that suggests fish are capable of feeling pain. Some may argue that this pain is not the same as humans feel, but does that really matter? Who are we to decide that human pain is the benchmark of acceptable suffering? Land mammals certainly feel pain, as we can observe their responses more clearly, but we have no evidence their pain is the same as ours, yet we still afford them legal protections. Why are they thought of any differently to fish?
Our view is that all suffering should be avoided at every opportunity, regardless of how much we understand about that suffering. The best way we can do this, is to go vegan and stop supporting the fishing industries that cause suffering in millions of fish every day.