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.
Using fish to study the impacts of Climate Change
Fish were either bought or caught and killed so that they could be dissected.
Overfeeding Zebrafish to learn about obesity
Normal and transgenic zebrafish were fed normally or way too much. The fish were taken out of the water for glucose tests and blood samples.
Studying gut bacteria in fish
Nine fish were caught by underwater spearing and killed so that samples could be collected from their digestion tracts.
Studying the sleep of sharks
Sharks were caught and kept in outside tanks. For the experiments, they weren't fed for at least 4 days, of which they spent 3 days in a measuring chamber not much bigger than the shark. Oxygen consumption and behaviour were continuously recorded for the last 24 hours.
Infecting fish larvae as a potential model for humans
Zebrafish larvae were injected with bacteria to test how their immune system responds. This was repeated to test how well the immune system reacted and how long the effect lasts.
Finding a “growth gene” in snappers
Snappers were caught from the wild and bred. Around eighty-thousand of their offspring were hatched and raised. At regular “grading” events, injured and deformed fish were disposed of. At just under a year old, around twenty-two-thousand were left and transported to a sea pen, where they were raised to 17.5 months old before harvesting.
Testing how much fat you can feed fish
Fish in aquaculture were divided into groups and fed diets with different fat content. Fish were anaesthetised and faeces samples squeezed out of them.
Testing fish for mercury contamination
Wild fish were caught, measured and frozen to be analysed.
Measuring how stress affects fish
Fish were exposed to chronic stress for four weeks, while 57 non-stressed animals were kept as a control. Signs of stress were noted. At the end of the experiment, all were chilled to death.
Exposing fish to herbicides
Zebrafish were kept in tanks that were contaminated with different herbicide concentrations for 10 days. They were then mated to herbicide-exposed or control fish. Both generations were tested on behavioural changes at around 4 months of age. 24 fish per treatment were killed and dissected.
Testing supplements as protection from toxins in over 1,000 fish embryos
Embryos were harvested and kept in Petri dishes for toxicity and treatment tests. Embryos were treated with an antioxidant, a gold salt or both on the first day, and abnormal development was measured on day 5.
Studying effects of drying rivers on mudfish
Water depth and quality were measured at 24 different sites. Several traps for fish and invertebrates were set at 8 visits, sampling and mostly killing the caught animals (including 15 individuals of the endangered Kōwaro).
Studying bacterial spread in fish larvae
Bacteria were genetically modified and made fluorescent. Zebrafish were bred, and their larvae were infected with the bacteria. The fish were killed for analyses or used for live imaging under a microscope (and then killed, most likely).
Investigating effects of invasive fish removal
Using fyke nets and electrofishing, fish were caught on four occasions. Fish were marked with fin clippings around one big removal event where 3 tonnes of fish were caught. In recaptures a week after each marking event, invasive fish caught were killed after the examination.
Studying fish life cycles
Fish were sedated and their blood and ovarian tissue were sampled three times.
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 motherly instinct towards foster pups
Mice of different “status” (never pregnant, pregnant, new mums) were made to rescue foster pups they didn’t know from several places. Transgenic mice lacking a prolactin brain receptor were tested for anxiety behaviour in the standard elevated-plus-maze.
Testing new cancer vaccines
Mice were injected with cancer cells, followed by one of several potential vaccines. They were killed when tumours reached a certain size, or it became otherwise inhumane to keep them alive.
Testing if pregnancy affects the healing of teeth
Pregnant and non-pregnant mice were taken. After the pregnant ones gave birth, all mice were anaesthetised. Some of their teeth were forcefully moved. Two weeks later, all were killed.
Testing the effect of obesity during pregnancy
Pregnant mice were fed high-fat diets and had their babies removed via caesarean section. The foetuses were decapitated. Other newborn mice were separated to record their calls.
Testing how motherly mice are
Transgenic mice were compared to “normal” mice on rescuing pups and how they care for their babies. They were mated, gave birth, and then put through behavioural tests involving newborn mice. After a few weeks, they were killed.
Testing a medicine against drug addiction
Mice's tails were dunked in hot water. Rats were put through cycles of drug-seeking and withdrawal using self-injection of cocaine. Other rats were injected, and their behaviour was tested (with the notorious Forces Swim Test, among others).
Teaching animal researchers
A range of animals is used to teach researchers handling and experimental methods.
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.
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 infected with worm eggs to see if parasites from cattle can infect sheep.
Using sheep to try and model how well humans will heal after dental surgery
Sheep had healthy teeth pulled out and the sockets treated in different ways to compare how well the body will heal after a tooth is removed when left untreated vs using a bone graft.
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, to test different pneumonia vaccines for sheep.
Testing the effects and wash-out of painkillers
Lambs were treated with different painkillers or no painkillers at all before tail docking and castration. Their behaviour was monitored.
Developing “hyperimmune” milk
Sheep were injected with Covid-19 vaccines to see if they produced milk that could be marketed to consumers as providing immunity against certain diseases.
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
Lambs were tested and killed to assess the relationship between methane emissions, carcass weight and meat quality. 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 and compared with others without clips. Measuring devices were added before injecting different chemicals into the hearts of the conscious sheep.
Comparing success of muscle repair surgery with or without weeks of delay
Sheep were anaesthetised and one side of a pelvis muscle was detached. After several weeks, the muscle was repaired. How well the sheep then walked was noted 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.
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.
