Fish were the single most used species for science in 2020.1 Most were used in basic biological research (the study of living things and their processes) and were also used in animal husbandry research, species conservation, and more.
Why so many fish are used: Most fish have a very short reproductive cycle, meaning they can be bred quickly, they also don't generally cost much to breed or house, making them desirable test subjects in science.
Zebrafish are regularly used as animal models for human development. A single pair of zebrafish can produce 100 to 300 embryos in one week. Zebrafish embryos are transparent and have their whole “body plan” laid down only 2 days after fertilisation. The similarity between human and zebrafish genomes is often cited as a reason to use them in models.2
Snapper3, eels4 and other fish that are eaten5 are also regularly used in science because of their importance to the commercial fishery. This industry will always be looking for ways to maximise its profits.4
Many fish living in the wild are studied as a way to research climate change.
Fish in NZ have been used for:
1. Research into optimising the growth and use of fish for human consumption. This includes research into optimal feeding, genes responsible for body size and growth speed.
Other examples include:
- Testing environmental influences and impacts (i.e. how salmon farms affect surrounding ecosystems).
- Researching how toxins accumulate in fish organs (i.e. algae toxins, mercury).
- Finding treatments/vaccines for illnesses and injuries from aquaculture.
- Manipulating the life cycle of fish to try and maximise reproduction.
2. Teaching purposes in schools and universities, including observational activities and dissections.
3. Medical research (i.e., they are used to try and model humans).
Examples include:
- Fish larvae have been used to try and model human immunity.
- Fish embryos have been used to try and study human foetal development.
- Genetically modified fish have been used to try and study adipostasis and glucose metabolism.
4. Basic research into fish biology, including research into how sharks sleep, how hearing develops in fish, microbes inside fish stomachs and the spread of viruses in wild fish.
5. Research into the effects of climate change, including research into marine food webs, biodiversity changes, species behaviour and interactions and predator abundance.
Other examples include research into:
- Measuring the genetic reactions to stress.
- The effects of herbicides on fish behaviour
- How well Arctic fish do at higher temperatures.
6. Species conservation, including research into killing unwanted species (i.e., koi carb, catfish, rudd, and goldfish).
Other examples include research into:
- The efficiency of one-way barriers on lake outflow.
- Fish-friendly flood pumps (i.e. for eels).
- Finding out where wild fish breed the most (to see which areas are worth protecting).
- Optimising catching/tagging methods for re-capture projects.
7. Ecotoxicity testing (i.e., in tests that measure how biological, chemical or physical stressors affect ecosystems).
Places that use fish for science in NZ include universities, crown research institutes, polytechnics, commercial organisations and others.
The University of Otago for example has its own Zebrafish Facility. The MPI naturally has a research interest in fisheries and ecosystems. As a crown research institute, NIWA’s research in the fields of aquaculture, fisheries, and the Antarctic is funded by the government. Cawthron Aquaculture Park is home to a dedicated Finfish Research Centre (FRC), which opened in 2018 with funding support from the Ministry of Business, Innovation and Employment (MBIE).
Fish used for science in NZ are sourced from breeding units, fish farms, commercial sources, and public sources, are born during projects or are captured in the wild.
Discover real-life examples of how fish have been used in NZ below!
Measuring thickness of blood vessel walls
Colony cats were anaesthetised, and the blood vessels under their tongue were measured with a special hand-held camera.
Collecting faeces for lab tests
Colony cats were fed different diets for three weeks before their faeces was collected for analyses.
Surveying caregivers on their cat feeding
New Zealand cat caregivers filled in an online survey about their household demographics and what/how they feed their cats.
Testing new toxin in Hawke’s Bay (again)
Toxic bait traps were placed on a property in Hawke’s Bay. Cat population changes were monitored with stationary cameras.
Assessing stress reaction to anaesthesia in cats
Cats were put through several anaesthetic infusions with six-day breaks in between. Regular saliva samples were taken 24 hours before and after, and urine was collected through a wire mesh tray.
Trialling ready-made toxic bait
Toxic bait stations are set up in a regular pattern in an area and left for two weeks. Trial cameras and tracking tunnels monitor the effect on the population.
Studying medical data of cat and dog CT-imaging
Medical data from cats and dogs were gathered, and animals that had been euthanised for other reasons were examined.
Testing if a human diabetes drug might also work in cats
Research cats were placed in individual cages four times (one week each time) and injected with either a diabetes drug or a control solution. Several blood and urine samples were taken.
Testing a cat food supplement for tooth health
Colony cats were anaesthetised, and all plaque was removed from their teeth. Four weeks later, new plaque build-up was measured.
Sampling cats for feline immunodeficiency virus (FIV)
Buccal swabs (inside the cheek) were collected from almost 200 cats at 15 veterinary clinics.
Testing food preferences of cats
Cats were fasted for two hours in the mornings and then presented with different foods (lamb and beef parts) to measure their consumption.
Monitoring wild cats for a year
Wild cats are trapped and fitted with GPS collars. After one year, they are recaptured and killed.
Trialling a lighter rifle to kill trapped wild cats
Captured wild cats were shot in the head using an air rifle and were assessed to confirm death by recording the time to loss of heartbeat.
Testing a predictive marker for cancer survival in cats
Veterinary samples of cats with this form of cancer were analysed and compared with their remaining survival since diagnosis.
Monitoring outdoor cat behaviour
Privately owned cats with outdoor access were fitted with camera and GPS collars for up to three days.
Testing a diagnostic for feline coronavirus
Cats with specific symptoms were used to take blood, tissue, and fluid samples. Some blood samples were taken from control cats.
Investigating how worms spread between lambs and calves
Lambs and calves were treated against parasites and then infected with worm eggs. Infection status was monitored. This was repeated several times before all sheep were killed.
Testing a fertility treatment
Cows with fertility problems were treated with hormones for ten days or left untreated. All were then artificially inseminated.
Testing a supplement for more calcium intake
Pregnant cows were fed with or without a specific feed additive. After birth, all were fed the same diet. Blood samples were taken in the weeks around birth.
Checking endometritis rates in dairy herds
Some cows in several dairy herds were selected, and their vaginal discharge was measured and sampled. They were then impregnated as per standard agricultural practice.
Comparing weight gain with different diets
Newborn calves were raised on various milk, pasture, and pellets combinations. They were slaughtered at two years old, and their “quality” was measured.
Testing pain meds for disbudding
The horn buds of young calves who were slightly sedated were burned off with a hot iron. Half of them received pain meds beforehand, and blood samples were taken before and after. After 24 hours, the second group received pain meds, too.
Studying Ikeda infection and treatment
Regular blood samples were taken from cows on three different farms. Only some were treated against the parasite. Milk production and fertility were recorded.
Studying diarrhea infection
New mother cows had blood samples taken. If the sample was negative for a diarrhoea virus, they were sampled again after a while.
Studying genes for body size
Udders of dairy cows were slightly cut with a scalpel, and a tissue sample was taken with a biopsy needle.
Testing toxicity of a potential new fertiliser
Pigs were fed toxic bait and monitored until they died.
Studying stress around birth
Blood samples were taken from cows with a high or low risk of health concerns after birth.
Studying genetics of a missing tail
Cloned foetuses were implanted into female cattle to research taillessness. Some of them were killed during pregnancy to examine the foetuses. One tailless animal was killed at age 4, and one of the cloned calves died after birth.
Studying Ikeda (parasite) infection
Blood samples were taken from dairy cows and their calves directly after birth before separating them. After four months, the calves were sampled again.
Studying Osteoporosis in cows
Young female cattle who had given birth for the first time were sent to slaughter. Half of them had broken bones for between 2 and 10 days. Blood samples were taken before slaughter, and bones were collected after.
Testing a tuberculosis vaccine
Male calves were infected with bacteria. Two groups were vaccinated before or after the infection, and the third group was left untreated. All were killed and dissected 13 weeks later.
Testing feeding plans for better immunity after calving
Pregnant cows were fed either a bit too much or a bit too little. Blood samples were taken before, at, and after calving. Researchers also took liver samples with a 20-cm biopsy needle and vaginal samples with a small brush and a scoop at these dates, except for the date of birth.
Testing dogs’ preception of time
Dogs were trained to press different levers based on their exposure to different types of light.
Testing working dogs for a gene mutation
Buccal swabs (inside the cheek) were collected from working dogs to analyse their DNA.</p><p id="">Procedure: Buccal samples were collected from 100 working farm dogs. Their owners were approached at gatherings such as Working Dog Trials, veterinary clinics and farms. Swabs were taken under the owner’s care. No adverse effects from the sampling were reported.
Determining how common E. coli is in pets
Rectal swaps were taken from cats and dogs presented at veterinary clinics, and their caregivers filled out a questionnaire.
Testing interest of dogs in different kiwi bird items
Dogs were taken to a small area to interact with different items that looked or smelled like kiwi bird. Some dogs had patches of hair shaved off to attach a heart rate monitor.
Teaching dogs to smell out koi carps (2018)
Five pet dogs were trained over several months to identify the smell of koi carb from water samples.
Measuring lean body mass of working dogs
Blood samples were taken from dogs, while they were deprived of water for 2 hours.
Testing a possum poison for other animals’ safety
Dogs were fed dead possum, either whole or minced. Once they got used to eating this, they were fed with possums killed with sodium nitrite, and signs for poisoning were monitored. In the end, all animals were killed and dissected.
Investigating separation anxiety in Greyhounds
The occurrence of separation anxiety with rehomed Greyhounds was investigated over one year.
Investigating a muscle weakness disease in dogs
Blood samples were taken from dogs with signs of myopathy within the regular veterinary treatment. A total of 22 of the 86 cases were euthanised.
Analysing CT scans of dogs
Veterinary data of German shepherd dogs were analysed; most were police dogs.
Testing if bone marrow is different in different body parts
Dogs were killed, and samples of their bone marrow were taken from different locations on their bodies.
Practising vet skills on different species
Students are taught anatomy, physiology, animal handling and basic clinical/husbandry skills. Dogs were used in for training in anaesthesia classes.
Assessing blindness in racing greyhounds
Greyhounds were treated with pupil dilation drops to examine their eyes. Some were brought to a vet clinic for further tests.
Testing a possum poison for other animals’ safety
Dogs, chickens and wild-caught cats were fed dead possum. Once they got used to eating this, they were fed possums killed with sodium nitrite, and signs for poisoning were monitored.
Testing nutritional value of new pet food
Cats and dogs were fed a test diet exclusively for several months. Some adults are kept in metabolic chambers for 10 days, and blood samples are taken at the end.
Scanning spines of dogs in CT
Police dogs and racing Greyhounds were sedated and computed tomography imaging was taken.
Studying fish behaviour in groups of multiple species
Mixed-species groups of fish (partly caught in the wild) were placed in a tank and fasted for 24 hours. Food was given and an artificial predator was used to study behaviour.
Studying food chains near CO2 vents
Fish and snails were observed and counted near CO2 vents and at control sites. Fish were also caught to examine their stomach content.
Studying fish behaviour in single-species groups
Young fish were caught in the wild and split into groups of 15, 75, and 150 animals. After being fasted for 24 hours, food was given and an artificial predator was used to study behaviour.
Testing the side-bias of fish (if they prefer to swim left or right)
Wild-caught fish were kept for 1.5 years before each fish was placed on a runway to observe their behaviour. Afterwards, fish were observed for schooling movements and some were killed to dissect their brains.
Studying effects of Climate Change on farming in damselfish
Fish were observed for their algae farming behaviour near CO2 vents and at control sites (Bay of Plenty). Small areas were covered to keep the fish away for a month and compare algae growths measured to compare.
Trying to estimate habitat quality from body condition
Snappers were hatched from eggs and raised on commercial food. They were kept in 800-litre flow-through tanks containing 170 to 260 fish each. At 80 days, they were fasted killed.
Trying different techniques for tagging fish
Fish were bait-trapped and treated for parasites. They were used to test different tagging methods. In the second part of the experiment, fish were caught with two different methods, after which injuries and survival over 12 days were monitored.
Studying fish near volcanic vents to learn about Climate Change
Fish near volcanic CO2 vents and at control sites were observed and counted. The reaction to baited underwater cameras and predator threats was filmed. Aquarium experiments were conducted with caught fish of different species.
Verifying “fish-friendly” flood pumps
Eels were caught, measured and tagged with transponders into the gut skin. They were later re-captured, observed for wounds and fungus and killed to examine internal damage.
Testing the temperature tolerance of Antarctic fish
Wild-caught fish were kept individually for months in tanks. During temperature experiments, fish of each group were tested for their breathing ability in small tubes before all fish were killed.
Slowly poisoning fish
Snappers were fasted for three days and then fed with toxic fish. Several died during feeding, and the rest were killed at the end.
Studying population changes in reef fish
Over 1,000 fish were caught by spearing at three NZ locations.
Testing the hearing of fish
Fish were anaesthetised and strapped to a plastic slide near an underwater speaker. Electrodes were placed in their head and gills to measure brain activity. For medical imaging, fish were restrained in a plastic tube with a sponge to keep them wet.
Developing a model for thermal stress in humans
Guinea pig pups were lightly anaesthetised, connected to devices measuring heart activity and breathing, and wrapped in a temperature-controlling blanket. Their body temperature was either forcefully raised or dropped.
Testing how too much fructose is bad during pregnancy
Female guinea pigs were mated; some were fed additional sugary water until birth. The pups were used for several glucose tolerance tests and X-rays. All pups were killed in the end.
Testing a seizure medicine for preterm babies
Pregnant guinea pigs were induced to give birth early, to test medication on their pups.
Testing the effects of sedatives
Young guinea pigs were treated with different sedatives. Their heart rate and blood pressure were measured before and during each treatment.
Testing an refined way of anaesthesia in guinea pigs
Guinea pigs were made to inhale anaesthetic gases. Different probes were inserted and attached to the animals to measure responses.
Studying the effect of fructose during pregnancy
Guinea pigs were fed either normally or supplemented with fruit sugar before and during pregnancy until birth. Mothers and pups were tested for glucose tolerance.
Studying the effects of meth
Guinea pigs were injected with sedatives, caffeine, and later meth. Under anaesthesia, their livers were cut out before they were killed.
Studying preterm birth effects on the brain
Pregnant guinea pigs were grouped to give birth normally or be induced early. The pups were put through behavioural tests and then killed for dissection.
Studying trauma and treatment of cochlear implants
After destroying their hearing with noise, guinea pigs were fitted with cochlear implants. Treatment success was tested before they were killed.
Testing the measurement of pupil reflexes in Alzheimer’s research
Guinea pigs were repeatedly flashed in the eyes with a phone light to record the pupil responses.
Teaching animal researchers
A range of animals is used to teach researchers handling and experimental methods.
Investigating mechanisms slowing down the heart rate
Young guinea pigs were injected with blood thinner before being anaesthetised and dissected.
Testing a device to assess hearing
Young guinea pigs were anaesthetised, electrodes placed under their skin, and their brain's response to sound was measured. All guinea pigs had one ear damaged, some both ears, before all were killed.
Studying changes in the inner ear due to inflammation
Guinea pigs were injected into the ear with bacteria. Medical scans were done after injecting chemicals, and most were killed for dissection.
Studying the effects of medication on memory
Guinea pigs were force-fed different drugs and later tested in a water maze before some were killed. Another group was exposed to carbon dioxide and decapitated.
Studying how anaesthetics affect intestine movement
Guinea pigs and rats were anaesthetised, then dissected, and then killed, in that order.
Testing a UV treatment for bacterial eye infection
Pigs’ eyes were acquired for testing a new treatment, followed by tests on live mice, most of whom were killed.
Studying methane emission and meat quality
Sheep were bred for high and low methane emissions. Almost 2,000 were put through emission measurements. Over 17,000 were slaughtered.
Testing if anaesthesia affects the sleep–wake cycle
Mice were kept on a 12-hour light/dark cycle and then switched to total darkness. They were anaesthetised twice to see the effect on their activity cycles, and all were killed in the end.
Testing the influences on growth
Transgenic and "normal" mice were kept in small groups and killed at different ages. Fat and muscle tissue were dissected, and the hearts were taken.
Testing a new way to kill lab mice
Mice were fed cream cheese containing different amounts of a sedative. Behaviour was recorded during the sedation period and while gassing them with CO2.
Testing a possible cause for cataracts
Transgenic and "normal" mice were used to study the development of cataracts. They were anaesthetised, images of their eyes were taken, and then they were (likely all) killed.
Studying chronic stress
Mice were handled daily, had vaginal smears, and some were subject to the notorious Forced Swim Test. Half of them were additionally stressed daily in various ways to see the difference it makes.
Trialling cancer drugs in mice after similar drug failed in humans
Mice were force-fed daily with two new drugs in different dosages. Others were force-fed a control solution, and some were left untreated. In the end, the animals were killed with CO2 and dissected.
Testing if exercise influences treatment success with cancer
Mice were injected with cancer cells. When tumours reached an “ethical” limit, they were injected with a labelling agent, anaesthetised and killed to be dissected. This was repeated, while some mice received cancer treatment.
Testing if exercise influences muscle mass with cancer
Mice were injected with cancer cells, and some received immunotherapy once the tumour reached a specific size. When tumours reached an “ethical” limit, they were killed. Cancer-free control mice were killed simultaneously.
Studying the interaction of hormones and stress
Transgenic mice had their brains injected, some had their ovaries removed, and some were restrained for repeated blood samples. In the end, all mice were killed.
Studying movement processing in the brain
Transgenic mice were put through behavioural tests while half of them had a part of their brain-damaged. Some mice had a window put into their skull to take recordings of their brains while awake. They had limited access to water and were forced into a device that stopped them from moving their head. In the end, all were killed.
Testing seizure activity in transgenic mice
Mice with specific genetic limitations were bred. Some were killed for dissection, and others were injected with a gene activation drug before they were killed.
Testing a seizure treatment
Genetically modified mice had wires and a cannula implanted in their brains, and were injected to cause seizures. The next day, their genetic mutation was activated. The test was repeated before they were all killed.
Observing cancer growth with/without treatment
Mice were injected with human breast cancer cells. The growth was monitored and sampled (biopsy). Some were operated on to remove their ovaries and some were treated with drugs before all were killed.
Testing how hormones influence activity while pregnant
Transgenic and “normal” mice were used to test the influence of pregnancy and hormones on activity and anxiety. They were kept in single cages with running wheels and subjected to behavioural tests. The transgenic mice were killed in the end.
Studying the effect of certain lipids in formula on brain development
Piglets were kept individually and fed formula with different supplementation. After 18 days, they were killed.
Harvesting bladders to study contraction patterns
The bladders of six pigs were surgically removed under anaesthesia before the pigs were killed.
Testing the effect of a shot to the head
Pigs were anaesthetised and shot in the back of the head from different distances. Effects were recorded and analysed.
Training students in surgical procedures
Pigs and sheep were used for training future surgeons.
Teaching students surgical techniques
Sheep and pigs were used and killed in teaching students.
Testing the viability of xenotransplantation using islet capsules
Newborn piglets were killed for their pancreas. Encapsulated pancreas cells were then implanted into young mice, who were killed later to retrieve the capsules.
Testing measurement of specific proteins
Pigs were surgically fitted with an outside access to their intestine and kept individually for eight weeks. Digestive matter was collected over ten hours on one day, while the pigs had no access to food or water.
Studying the spread of bovine tuberculosis in pigs
Pigs were bought, and wild pigs were captured and distributed through two studies over almost two years. Pigs were killed regularly to dissect them for tuberculosis signs.
Studying wound healing treatments
Pigs were anaesthetised and wounded in 20 places on their backs. The wounds were treated differently and sampled over a month before the pigs were killed.
Developing a model for varicose veins
Blood vessels in pigs' legs were surgically altered, and some pigs were fitted with devices to measure blood pressure. After weeks of regular examinations, all were killed.
Testing how long you have to wait to shoot and eat poisoned wild pigs
Piglets were fed different amounts of rat poison for longer or shorter periods before they were all killed.
Testing how many cancer cells spill out during colon surgery
Pigs were anaesthetised and injected with radioactive cancer cells. Different colon surgeries were performed.
Comparing effects of anaesthetics on breathing and heart rate
Guinea pigs, rabbits and rats were anaesthetised, and a tube was put into their windpipe through the neck. They were made to breathe anaesthetic gas.
Investigating how worms spread between lambs and calves
Lambs and calves were treated against parasites and then infected with worm eggs. Infection status was monitored. This was repeated several times before all sheep were killed.
Using sheep to try and model how well humans will heal after dental surgery
Sheep were anaesthetised, three teeth were pulled, and the sockets were treated differently. For months, regular samples were taken from the healing wounds before all sheep were killed.
Preclinical testing of a gene therapy for Batten disease
Sheep with and without a specific gene mutation were checked and scanned regularly for nine months. Affected sheep received gene therapy at different ages. Treated sheep were killed.
Testing if blocking a cell signal can prevent foetal brain injury
Pregnant sheep were anaesthetised, and the foetuses fitted with electrodes. The umbilical cord was blocked for most of them, and half were treated with a test drug. Mothers and unborn lambs were killed three weeks later.
Testing the combination of drugs for congestive heart failure treatment
Sheep were anaesthetised and subjected to surgery. Electrodes were used to pace their hearts faster while testing the effect of different drugs.
Testing the best way to deliver gene therapy drugs
Sheep were anaesthetised. Their heads were drilled into, and their brains injected with test drugs. They were killed after three weeks.
Testing the potency of pneumonia vaccines for sheep
Lambs were vaccinated twice, and regular blood samples were taken for 34 weeks.
Testing the effects and wash-out of painkillers
Lambs were treated with different painkillers or not at all before tail docking and castration. Their behaviour was monitored.
Developing “hyperimmune” milk
Sheep were injected with Covid-19 vaccines, and regular blood samples were taken. Some were mated and gave birth to sample their milk, too.
Studying the genetics of Batten disease on chimeric lambs
Sheep foetuses were removed. After swapping cells between them, they were inserted into other ewes. Lambs born were subjected to X-rays and, at one to three years old, were bled out for dissection.
Testing pacemaker adjustments
After causing them heart failure, sheep were surgically fitted with pacemakers and measurement devices. Those who survived the procedures were killed after six months.
Studying methane emission and meat quality
Sheep were bred for high and low methane emissions. Almost 2,000 were put through emission measurements. Over 17,000 were slaughtered.
Studying the effect of chemicals in normal and high blood pressure
Sheep were surgically fitted with a clip around an artery, or they served as control. Measuring devices were added before injecting different chemicals into the hearts of the conscious sheep.
Comparing muscle repair success with and without weeks of delay
Ewes were anaesthetised, and one side of a pelvis muscle was detached. After several weeks, the muscle was repaired. Gait was evaluated before all were killed.
Comparing different designs of dental implants
Sheep were anaesthetised. One leg bone was exposed and fitted with several implants. After 12 weeks, all were killed.
Trying to model human brain injuries
To study changes in different areas of the brain after brain injuries. Sheep were used to study the effects of traumatic brain injuries in humans.
Questioning vets on pain management
Veterinarians completed a questionnaire regarding pain and pain management in rabbits and guinea pigs.
Testing immunity assays for RHD virus
Wild-caught rabbits were injected with Rabbit haemorrhagic disease (RHD). All that did not die were killed.
Testing treatments for another medication overdose
NZ White rabbits were anaesthetised, and catheters were placed in blood vessels and intestines. After poisoning them with an overdose of medication, different treatments were tested for one hour.
Testing treatments for anaesthesia overdose
NZ White rabbits were restrained, fitted with catheters and needle electrodes and then given an anaesthetic. Saline or lipid solutions were given, and the reaction was monitored.
Testing retention time of eye medication
NZ White rabbits were restrained, and medication was put into their eyes. The reaction was recorded.
Harvesting rabbit and rat hearts for lab tests
NZ White rabbits and rats were killed to use their hearts in lab tests.
Testing a treatment for medication overdose
Rabbits were anaesthetised, and devices measuring blood pressure and heart rate were placed. After testing a toxicity treatment, all were killed.
Testing different treatments for medication overdose
NZ White rabbits were anaesthetised, and devices to measure their circulation were placed. Their hearts were stopped, and “first aid” was performed before all were killed.
Testing a treatment combination for medication overdose
NZ White rabbits were anaesthetised devices to measure their circulation were placed. Their hearts were stopped, and “first aid” was performed before all were killed.
Studying rabbit eyes to learn about human glaucoma
Dutch black-belted rabbits were anaesthetised and killed. Their eyes were removed and studied.
Comparing effects of anaesthetics on breathing and heart rate
Guinea pigs, rabbits and rats were anaesthetised, and a tube was put into their windpipe through the neck. They were made to breathe anaesthetic gas.
