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 infected with worm eggs to see if parasites from cattle can infect sheep.
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.
Analysing Greyhound race injury statistics
Historical data on Greyhound races between 2014 and 2019 were analysed. Injuries and deaths were investigated.
Using bones of euthanised shelter dog
Cadavers of dogs killed at an animal shelter were donated. Holes were drilled into leg bones and fitted with screws.
Investigating farm dogs for four years
Working farms dogs were examined regularly for four years. Health problems and fate were recorded.
Transplanting faeces as diarrhoea treatment
A dog with diarrhoea was treated with laxatives and warm water before a faeces sample from a healthy dog was inserted into his colon. Samples were taken before and after.
Testing the eyes of working dogs
Eye examinations were performed on working sheep dogs. Medication for pupil dilation was given, and faeces samples were taken from most dogs.
Analysing dog movements
Colony dogs were prepared with reflective markers and an activity collar. Their movements on a treadmill at various speeds were recorded.
Testing the effect of diet on farm dog performance
Working dogs were fed a diet very high or very low in carbohydrates. Their blood glucose and activity were monitored three times over four days each.
Testing a parasite treatment
After a pilot study with just one dog, six more were given an experimental parasitic treatment. Regular blood samples were taken through a catheter.
Teaching dogs to smell out catfish
Five pet dogs were trained over several months to identify catfish and goldfish smell in water samples.
Testing different combinations of pain meds
Eight dogs are treated with four different combinations of the test drugs in random order with two-week breaks in between. Two catheters are placed in leg veins (for drug injection and blood samples). For the test, dogs are fasted for 12 hours and anaesthetised. EEG is recorded with electrodes near the brain to measure response to electric shocks. Regular blood samples are taken for 8 hours.
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.
Teaching dogs to smell out koi carps (2019)
Three pet dogs were trained over several months to identify koi carb smell in water samples.
Testing working dogs for internal parasites
Faeces and blood samples were taken from working farm dogs.
Testing fluid management of dogs during anaesthesia
Dogs were anaesthetised. Their heart activity was measured while hey were injected with calculated amounts of fluid.
Trying to make rat poison unattractive for dogs
Dogs were fasted overnight and then given two food bowls with different kinds of repellent on one of them.
Surveying respiratory disease in racing Greyhounds
Laboratories sent in serum samples of dogs for analysis. Additionally, 17 racing Greyhounds were tested.
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.
Researching scoliosis genes
Transgenic mice with a specific gene defect were mated. Pregnant mice were at several time points. The unborn babies were taken, skinned, and gutted to stain their skeletons for better pictures.
Studying hormone influences on obesity and fertility
Transgenic mice were bred to have diabetes symptoms. Together with control mice, they were fed a normal or a high caloric diet and compared for their fertility over 150 days.
Testing a new stroke treatment
Mice were squeezed into plastic cones, and test drugs were dripped on their nose. An artificial stroke was caused by injecting a chemical into their brain. Before and after, mice had to perform behavioural tests. All were then killed to take their brains.
Testing another new stroke treatment
Mice were operated on several times. They were made to experience an artificial stroke, were later injected with a possible treatment, and then were injected with a marker. The mice had their memory tested before they were killed.
Testing prostate cancer drugs
Mice were anaesthetised, and their prostate was injected with cancer cells or a control solution. A 42-day treatment course started three weeks later with different treatment drugs and control solutions. In the end, all mice were killed.
Testing a heart attack treatment
Mice were trained to eat jelly and then subjected to an artificial heart attack. They received either a new drug or a control substance. Regular heart ultrasounds were performed before they were killed and dissected.
Studying ovary problems caused by testosterone
Transgenic mice were implanted with a capsule containing either hormones or not. Vaginal smears were done for several weeks, and serial blood tests were performed twice. In the end, all mice were killed.
Testing an Autism treatment on transgenic mice
Mice were genetically modified to show "autism-like" symptoms. Together with control animals, they were either fed normally or with a high-zinc diet. Invasive behavioural tests were performed. At least some, likely all, were killed.
Comparing transgenic mice and humans
Mice were anaesthetised, and their body composition was measured several times. Their grip strength and balance were tested with lab equipment. In the end, all mice were killed.
Testing a new stroke drug for better dexterity
Transgenic mice were anaesthetised, and an artificial stroke was caused. They then received either a test drug or a control solution. After recovery, their food was limited to test their fine motor skills every other week. After two months, they were killed.
Testing migraine drugs
Mice were injected with potential migraine drugs and anaesthetised. Ultrasound imaging of their ears was taken. One ear was rubbed with capsaicin to record the increased blood flow and compare different drugs, doses, and time points.
Killing rats and mice for tissue
Rats and mice were anaesthetised, and their necks were broken. Their tissue was then used for research.
Studying Alzheimer’s and stroke symptoms
One group of transgenic mice were bred and killed at either four or 12 months of age by flushing their hearts. Another group was anaesthetised and caused to have a stroke. They were killed the same way.
Testing Alzheimer’s treatment on mice
Transgenic and “normal” mice were injected with a special protein and a chemical to mark new brain cells that may have been produced.
Testing a new Alzheimer’s drug
Newborn mice were killed to collect brain tissue. Adult mice were used to test drug reactions. They were anaesthetised twice; to inject the drugs and to flush their hearts and take their brains.
Testing if anaesthesia affects the sleep–wake cycle when combined with light treatment
Mice were kept on a 12-hour light/dark cycle and then switched to total darkness. During this time, they were exposed to light once, either with or without anaesthesia. The effect on their activity cycles was monitored. In the end, all were killed.
Harvesting colon tissue for laboratory tests
Pigs were killed and their colon tissue was used for laboratory testing.
Testing if pigs can be fed by-products from biofuel and food processing
Pigs were fed a standard diet or a diet containing by-products from other industries. They were slaughtered to compare meat growth and quality.
Studying starch digestion in pigs to try and model humans
Pigs were fed different diets containing durum wheat or rice. Some had regular blood samples taken through a catheter. All the animals were killed at the end.
Validating a treatment for stomach muscle dysfunctions
Pigs were anaesthetised, their bellies were opened, and electrodes were placed on their stomach walls before and after damaging some stomach tissue with heat. All pigs were killed.
Assessing pigs as digestion models for humans
Titanium tubes were implanted into pigs’ intestines. Digested food was collected through the tube for 9 hours.
Testing the effect of different species’ milk on brain gene expression
Piglets were fed different kinds of milk from other species for 15 days. They were killed to dissect their brains.
Testing transmitter implantation on wild pigs
Wild pigs were captured, and three different tracking devices were fixed to or implanted into each one. After 104 days, they were tracked down and killed.
Investigating oxygen content in the gut
Pigs were fed diets with different or no protein sources as a control. After a week, all were killed.
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.
Testing the effect of different species’ milk on protein digestion
Piglets were fed different kinds of milk from other species for 15 days. They were killed to dissect their stomachs.
Testing the strain on a temporary surgical implant
A surgical implant was screwed to a severed pig head, and measurements were taken via laser scanning.
Investigating intestine movements
Young pigs and NZ White rabbits were anaesthetised. A part of their intestine was pulled out far enough to record its movements and signalling.
Harvesting rabbit and pig eyes for lab tests
The eyes of slaughtered rabbits and pigs killed for experiments were used to analyse the structure of the cornea.
Harvesting eyes for lab tests
The eyes of pigs and rabbits killed for experiments were used to analyse the structure of the cornea.
Testing a treatment for stomach muscle dysfunctions
Pigs were anaesthetised, their bellies were opened, and electrodes were placed on their stomach walls before and after damaging some stomach tissue with heat. All pigs were killed.
Testing how electric stimulation affects stomach movements
Nine pigs were anaesthetised, their bellies were opened, and electrodes were placed on the stomach walls. Electric stimulation tests were performed before the pigs were killed.
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.
Testing out cloning as a breeding tool
Cloned embryos were implanted into 17 mother sheep but all the pregnancies failed.
Undernourishing sheep to test glucose metabolism of their babies
Sheep were fed normally or only every three days. Some were killed during pregnancy. Born lambs were subjected to repeated glucose tolerance tests and killed.
Testing a medication for vocal chord injuries
Sheep were anaesthetised, tissue samples were taken from their vocal folds, and most were treated with different medications. All were killed after one month.
Testing if pre-term birth injections compromise glucose metabolism
Pre-term and full-term lambs were subjected to glucose tests, regular blood samples and a constant glucose infusion. Some were killed at four weeks, the rest at one-year-old.
Studying the effect of Huntington’s disease on ageing
Transgenic sheep were produced through breeding, and blood samples were taken.
Testing a first aide drug for severe bleeding
Sheep were anaesthetised and 30% of their blood was drained. After being treated with different medications, the drained blood was returned, and the sheep were killed.
Studying ear posture while in pain
Lambs had their tails docked with a tight rubber band without pain relief. Their pain behaviour was recorded.
Teaching animal researchers
A range of animals is used to teach researchers handling and experimental methods.
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.
Studying effects of stunning before slaughter
Calves and sheep were anaesthetised. Some got 70-volt shocks to the shoulder. Others had a nerve exposed and stimulated before being stunned or cutting their throat.
Investigating intestine movements
Young pigs and NZ White rabbits were anaesthetised. A part of their intestine was pulled out far enough to record its movements and signalling.
Harvesting rabbit and pig eyes for lab tests
The eyes of slaughtered rabbits and pigs killed for experiments were used to analyse the structure of the cornea.
Causing sinusitis in rabbits as a model
NZ White rabbits were anaesthetised, and a sinus tract in their nose was blocked for four weeks to cause sinusitis. After another ten weeks with regular samples, they were killed.
Testing a new vaccine
NZ White rabbits were injected with a new vaccine type several times before being killed.
Harvesting eyes for lab tests
The eyes of pigs and rabbits killed for experiments were used to analyse the structure of the cornea.
Testing the toxicity of some substances
Young NZ White rabbits were force-fed different doses of toxic substances. Blood samples were taken before and immediately after killing them at set time points (or to end their suffering).
Using a new imaging technology
One NZ White rabbit and rats were killed, and their eyes were removed to use for the study.
Measuring contractions in exposed rabbit uteruses
Pregnant rabbits were anaesthetised, and their uterus was exposed. Measurements were taken while contraction-inducing injections were given. Then they were all killed for dissection.
Mapping wave patterns of the small intestine
NZ White rabbits were anaesthetised, their intestines were used for electrode mapping, and then they were killed.
Studying presence of a virus in rabbits
Wild rabbits were shot, caught by dogs or trapped to test them for virus strains. The infectious solution was then fed to NZ White rabbits in a lab to kill them later.
Harvesting rabbit colons for lab tests
NZ White rabbits were anaesthetised, a part of their intestine was cut out, and then they were killed.
Harvesting rabbit bladders for lab tests
NZ White rabbits were anaesthetised, their bladder was cut out, and then they were killed.
Testing an antimicrobial eye medication
NZ White rabbits were treated with Manuka honey solution in one eye and a control solution in the other eye for five days. Different values like tearing and irritation were measured.
Using muscles of dead rabbits for imaging
Two NZ White rabbits were killed to use for detailed muscle imaging.
Measuring jaw bone growth in young rabbits
Young rabbits were anaesthetised and had holes drilled into their jawbones to implant small pieces of metal. X-ray scans were made, and the rabbits were killed.
Testing the welfare impact of pindone toxin
Three groups of young NZ White Rabbits received pindone-toxin pellets on different schedules. Any rabbit still alive after three weeks was killed.
