siamese fighting fish intelligence

Catch and release fishing is cruel

How fish are harmed, proof that fish feel pain, why do fish let themselves be caught again, the myth that fish don't feel pain because they are cold-blooded.

Fish have keen senses and sensitive nerve endings, anglers cause suffering and death, and other animals are gravely injured.

All available evidence suggests that fish are capable of experiencing pain in much the same way as other vertebrate animals. Furthermore, the infliction of pain and suffering cannot be divorced from the spinal cord.

Without feeling pain, fish would not survive

The only way we could be certain that animals, other than the human species, are capable of feeling pain and suffering would be by their verbal confirmation of the fact. Unable to 'talk to the animals', we must rely upon our knowledge of animal biology and behavior to make reasoned assumptions. We know there are close similarities between 'higher' and 'lower' vertebrates in their biological make-up and the way the function of their nervous systems. Fish are actually not that much different from ourselves in that they also possess a heart, stomach, brain, spinal cord and intestines. Indeed, the basic internal organization of organs is similar for all vertebrate species.

The nervous system is an essential mechanism for survival. Fish, like other animals, must be aware of their surrounding" environment and' consequently are well-equipped with monitoring devices such as eyes, ears, nasal sacs, a lateral line and sensitive nerve endings. These sensory organs are connected to a central nervous system comprising the brain and spinal cord.

Torture after capture

All types of fishing (the taking of fish with rod, line and hook) necessarily involve the abuse of fish, but coarse fishing (the terms fishing and fishing are synonymous) is undoubtedly the cruellest. Whereas sea and game anglers usually 'despatch' their prey soon after capture, the coarse (freshwater) angler's (largely inedible) victim suffers a mauling and possible imprisonment before release.

A fish is deceived into impaling itself on a (usually) barbed hook, resulting in tissue damage - in medical terms, the infliction of an injury. The wound is aggravated by the prolonged tension of the fishing line as the angler 'plays' the fish to tire it and allow it to be landed.

When a fish leaves the water it enters an alien environment. Because removed from the water its tissues are subject to different pressures in air, the fish's gills collapse and breathing is virtually impossible. For a while some oxygen will be circulating in the bloodstream but this is soon exhausted. Bleeding may occur from the gills.

Hook retrieval may take some time - especially if the fish has "swallowed the hook". Damage is likely to result in an internal organ and then death.

During the handling process, a protective mucus covering, which provides the creature's waterproofing and protects it from fungal and bacterial infections, is damaged.

If the fish survives the ordeal of being caught, it is then either returned to the water, where it must devote its efforts towards recovery or is put into a keepnet - which is suspended in water. Such nets are stress-inducing and within them, physical damage may occur to the captive fish. Deoxygenation and the build-up of metabolic waste products can rapidly make conditions within the net adverse to the well-being of fish and foster disease.

Other fishing practices may add to the trauma. Fish may be examined, weighed and perhaps photographed before being liberated. All such procedures increase the likelihood of injury.

Other animals victims

Fish are not the only creatures to suffer. Lost and discarded fishing tackle is potentially lethal to wildlife - particularly waterfowl, which suffer lacerated beaks and throats by swallowing hooks or lose their feet and occasionally their lives by becoming entangled in non-biodegradable nylon line.

Report found that fish suffer

In 1976, The Royal Society for the Prevention of Cruelty to Animals (RSPCA) set up a Panel of Inquiry into Shooting and Angling, chaired by Lord Medway, it comprised leading scientists and representatives from shooting and fishing organizations. It is also known as the Medway Report.

The main finding of its report (published in 1980) as regards fish is that there is sufficient evidence to suggest that they are capable of suffering.

The report notes that there exist patterns of behavior in animals similar to the non-verbal responses of human subjects known to be suffering pain. In other words, vertebrates react similarly when a strong stimulus such as sharp pressure is applied - they will recoil, shudder, sometimes squeal and try to escape.

Medway also emphasizes that a distinction should not be made between warm-blooded and cold-blooded animals: "all vertebrate animals (i.e. mammals, birds, reptiles, amphibians and fish) should be regarded as equally capable of suffering."

It said that:

  • Angling is cruel
  • It is reasonable to assume that all vertebrate animals feel pain - including fish Keep nets cause a build up of gas and waste products, causing harm to the fish
  • When fish are taken out of water:
    • the lymphatic system is disturbed
    • blood pressure is disturbed
    • respiration is disturbed
    • coagulated blood forms around the gills
  • Injury is likely to occur as fish are examined, weighed, photographed and kept in nets
  • Handling of a fish damages its outer mucus layer. This can cause:
    • fluid imbalance with the surrounding water
    • entry of harmful micro-organisms
    • circulatory failure
  • Playing a fish with a fine fishing line can cause the line to break, leaving the hook embedded in the fish with the line attached
  • Double and treble hooks are likely to cause greater injury
  • Live baiting should be stopped
  • Public money should not be spent on promoting fishing

Fishermen's myths

Catch and release fishermen return their catch to the water unharmed

Recreational fishermen pride themselves on the 'fact' that unlike sea and game recreational fishermen, they return their victims seemingly unharmed. They delude themselves! Angling is probably the cruelest branch of the 'sport' since in the others, the fish are 'despatched' almost immediately on leaving the water. If a fish survives its period out of water, it is returned to suffer the consequences of its mauling in captivity.

Fish are prone to stress upon a change in oxygen concentration, temperature, sudden noise, vibration, and light intensity.

In a study in Finland, brown trout were transferred between tanks and then restrained for 5 minutes. This short procedure, not untypical of what fish suffer in recreational fishing, caused the heart rate to rise, and breathing to increase by nearly a third, for 3 to 4 days. (1)

Let us examine the cruelty involved in hooking, playing, and landing a fish.

A fish is deceived into impaling itself on a sharp hook resulting in injury. The fisherman may then 'play' the fish (particularly if a low breaking strain line is used) to tire it and allow it to be landed.

Leaving the water, a fish is unable to extract oxygen from the air and is subject to extreme stress. Fish have a protective mucus covering, which protects it from fungal and bacterial infections. This is disturbed when the fish is handled.

If a fish has swallowed the hook the hook's retrieval is very difficult, the suffering is prolonged and it is likely to result in damage to the fish's gut and subsequently death.

If the fish survives the ordeal of being caught, it is then either returned to the water, where it must devote its energy towards recovery or is put into a keepnet. Keepnets are an essential feature of match fishing where recreational fishermen compete with each other. The angler uses one for the satisfaction of gloating over the catch at the end of the session. Keepnets are stress-inducing and this is affected by their size, type, and the number of captured fish. Within the net, metabolic waste products build up and physical damage may occur to the imprisoned fish. Disease thrives in such an environment.

A freed fish has undergone a traumatic and disabling experience with perhaps fatal consequences.

Fish are only out of the water for a short time

The moment a fish leaves the water it enters an alien environment with which it is ill-equipped to cope. The gills collapse and breathing is virtually impossible. During the time that the fish is on the bank, it must live without oxygen. For a while, some oxygen will be circulating in the bloodstream but this is soon exhausted. Bleeding may then occur from the gills. Combined with the trauma of capture and handling, considerable stress is inflicted.

The longer out of the water, the greater will be the creature's suffering. Fish that 'swallow the hook' will remain out of water longer than those that are 'cleanly hooked'. The same applies to fish that the fisherman wishes to photograph. Match angling requires keepnets full of fish to be removed from the water for the often lengthy 'weighing-in' period.

Following the return to the water, a fish may remain motionless for long periods to achieve an oxygen balance and so function normally again. While resting, it is at risk of attack by predators.

It cannot be proved that fish feel pain

It is possible to recognize behavior patterns in animals similar to those found in human subjects known to be suffering pain. Pain teaches vertebrates to avoid what is physically harmful to them and is therefore an essential sense for survival.

In Moscow, Russian scientists tested the sensitivity of pain in cod, rainbow trout, carp, and sturgeon. Bursts of electricity to various parts of the fish's body. The fish responded by moving their tails. The most sensitive areas to pain were the tail, pectoral fins, the skin surface around the eyes, and the olfactory sacs. It was discovered that sensitivity to pain exists throughout the whole body, and that the pain threshold for fish was comparable to that in people. The scientists speculated that sensitivity in fish was necessary to detect damage during nest building and aggression with other fish. (2)

Because it has been known for fish to be caught twice in one day, fishing cannot be an unpleasant experience for the fish

This statement falsely assumes that a relationship exists between the frequency of capture and the capacity of fish to suffer. Scientific observation indicates that fish learn to avoid capture presumably as a consequence of associating being hooked, landed, and released with unpleasantness, and that subsequently they will tend to avoid an immediate repetition of the experience. Indeed, many recreational fishermen will admit that it requires unusual skill to entice a fish that has been repeatedly caught to take a baited hook. As with our own species, some individuals are slower to learn than others!

A hook cannot cause pain because fish eat shellfish and other spiky objects. The mouths of fish are designed to be lacerated

Fish have demonstrated that they remember the circumstances of painful experiences and will afterwards seek to avoid the same situation.

Sticklebacks receive some protection from predator fish through their sharp spines. In 1957 at Oxford University, researchers found that pike and perch initially snapped up, but then rejected, sticklebacks. Within a few experiences, the pike and perch learned to avoid the sticklebacks and the pain from the spines altogether. It was found that when spines were removed from sticklebacks, their protection disappeared.

stickback spines avoided graph

Dutch researchers in 1970 used recreational fishermen for three days to fish for pike, which had never been fished before, with live bait or spinner hooks. The fish were then tagged and returned to the water. It was then found that pike previously only hooked once by a spinner, rarely took it again, and avoided spinners for the remaining five days. (3)

The pike were fished again the next summer, together with unfished carp. Individual fish, and then the whole population of the two pools, learned, and then remembered, that the spinner was to be avoided. This memory lasted for at least one year.

Similar results were found with carp. This time, carp were able to remember their terrifying experience one year later, and, as with the pike, they were able to learn from the unfortunate experience of other previously hooked carp. (4) (5)

remembering fish pain carp decline graph

If fish felt pain they would swim towards the angler when hooked rather than resist and struggle to get free

Any fish will fight vigorously when hooked. Such behavior is both instinctive and natural. It is a typical characteristic of their primitive position in the vertebrate scale and their inherent will to survive. The frenzied struggle is the result of fear of the unknown or if previously caught, fear of being dragged into an unknown environment and another frightening experience. Fish are capable of only limited rationalization such as gradually learning to avoid a baited hook.

Some recreational fishermen draw an analogy with a bull being led by the nose, arguing that the animal follows to reduce the pain. It is reasonable to assume that the creature's ability to rationalize surpasses that of the fish. The behavior of the bull is based upon fear of the consequences of non-compliance, which manifests itself in the form of obedience. Like pain, fear is a natural and useful phenomenon, which promotes survival and self-preservation.

Fish cannot feel pain because they are cold-blooded

This unfounded assumption is held by a great many recreational fishermen; if challenged the user of such a statement would be hard-pushed to justify it in scientific terms. Its use, therefore, shows a considerable misunderstanding of fish biology.

The Medway Report commissioned by the Royal Society for the Protection of Cruelty to Animals, the largest animal welfare charity in the UK, stressed that all vertebrate animals, whether 'warm' or 'cold' blooded should be regarded as equally capable of suffering to some degree or another.

Fish do not feel pain in the same way that humans do

An angler using this argument has conceded that fish feel pain! However, the angler seeks to persuade us that it is of an inferior type to that experienced by humans.

Victoria Braithwaite, author of Do Fish Feel Pain?, said: "The evidence we have to support sentience and pain perception in fish is as good as anything we have for birds and mammals. Fish, like birds and mammals, have the capacity for self-awareness."


(1) Laitinen, M. and Valtonen, T., 1994. Cardiovascular, ventilatory and total activity responses of brown trout to handling stress. Journal of fish biology, 45(6), pp.933-942.
(2) Chervova, L.S. and Lapshin, D.N., 2004. Pain sensitivity of fishes and analgesia induced by opioid and nonopioid agents. In Proceedings of The Fourth International Iran & Russia Conference (pp. 1420-1425).
(3) Beukemaj, J.J., 1970. Acquired hook-avoidance in the pike Esox lucius L. fished with artificial and natural baits. Journal of Fish Biology, 2(2), pp.155-160.
(4) Beukema, J.J., 1969. Angling experiments with carp (Cyprinus carpio L.). Netherlands Journal of Zoology, 20(1), pp.81-92.
(5) Hoogland, R., Morris, D. and Tinbergen, N., 1956. The spines of sticklebacks (Gasterosteus and Pygosteus) as means of defence against predators (Perca and Esox). Behaviour, pp.205-236.
Fish Pain