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.
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.
Questioning vets on pain management
Veterinarians completed a questionnaire regarding pain and pain management in rabbits and guinea pigs.
Testing nerve reactions to electric stimulation
Young guinea pigs were bled to death. Specific nerves were removed and experimented on.
Studying short-sightedness
Guinea pigs had one eye covered for two weeks before increasing their eye pressure surgically and kill them.
Measuring nerve reactions to gases
Guinea pigs were anaesthetised, and their windpipe and blood vessels were cannulated. They were exposed to different gases and cyanide while measuring breathing and nerve activity.
Studying how anaesthesia affects breathing and heart
Guinea pigs were put in airtight chambers to test the effects of low oxygen. Some were surgically fitted with tubing so blood samples could be taken during the tests. In the end, all were killed.
Studying compensation after inner ear destruction
Guinea pigs were anaesthetised, and their inner ear was destroyed with a drill. Videos were made for over two days of their balance recovery.
Killing pregnant guinea pigs for tissue cultures
Pregnant guinea pigs were anaesthetised at specific time points of their pregnancy, including during labour, to then remove the uterus for tissue culture experiments.
Testing how oxytocin injections cause contractions
Pregnant guinea pigs were surgically implanted with electrodes on or near the uterus. They were injected with oxytocin in specific doses and timeframes, and the effects were measured.
Harvesting testicles for studies
Male guinea pigs were killed with CO2 to remove their testicles for experiments.
Testing a new tuberculosis vaccine
A new tuberculosis vaccine was tested by injecting guinea pigs with the bacteria, either with or without prior vaccination. After several weeks, all were killed.
Testing how heart calcium metabolism is different in species
Guinea pigs and rats were decapitated, and their hearts were quickly removed to study them.
Testing influences on the rate of a dissected heart
Albino guinea pigs were anaesthetised and dissected before they were killed.
Confirming the correlation of energy storage and stress in the inner ear fluid
Guinea pigs were anaesthetised and artificially ventilated. Ear fluid samples were taken through a hole in the skull, while exposing them to noise or lack of oxygen.
Comparing natural and genetically altered tuberculosis strains
Guinea pigs were infected with tuberculosis strains after being injected with bacterial proteins beforehand. In the end, all guinea pigs were killed and dissected.
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.
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.
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.
Testing out cloning as a breeding tool
Cloned embryos were implanted into 17 mother sheep. Two sheep were killed when induction did not work. The lambs survived only minutes.
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.
Testing efficiency of strip-sowing 1080 bait
The toxin ‘1080’ was distributed as complete coverage and in a strip pattern. Effects on the wild rabbit numbers were evaluated.
Testing new formulations of eye medication
The eyes of albino rabbits were treated with different medications. At regular intervals, several of them were killed.
Taking blood samples over several days
Two New Zealand white rabbits were anaesthetised and restrained. Catheters were put into their ear veins to inject a solution and take regular blood samples.
Harvesting rabbit caecum for more lab tests
Domestic dwarf rabbits were anaesthetised, their caecum was cut out, and then they were killed.
Using rabbits as a model for human atherosclerosis
NZ White rabbits were fed pellets with or without added cholesterol for 10 weeks. They were killed with anaesthetic and taking blood from their heart until it stopped.
Testing new drug formulations
NZ White rabbits were given a new drug formulation or ketamine. Righting reflex, paw withdrawal, and blood parameters were checked every minute.
Infecting rabbits with a virus to have more samples of it
Samples of dead wild rabbits were taken to collect virus material. The virus was then used to infect rabbits and analyse their tissue.
Injuring the sinus tract to test medication
NZ White rabbits were anaesthetised, and the sinus tracts in their nose were purposely injured to the bone. Two weeks after treatment, they were killed.
Teaching animal researchers
A range of animals is used to teach researchers handling and experimental methods.
Testing new drug formulations
Rats and rabbits were injected with a new anaesthetic, pinching their paw repeatedly to measure reflexes. Rats were giving the medication until they died.
Testing the behaviour of a drug in rabbits’ blood
NZ White rabbits were infused with different medications, and blood samples were taken regularly for 24 hours.
Testing a new drug delivery formulation
NZ White rabbits were injected with a radioactive solution, wrapped tightly, and recorded this way for 90min.
Placing metal into rabbits’ jaws
NZ White rabbits were anaesthetised, and metal spheres were placed into their jaws. X-rays were taken to measure bone growth.
Using rabbits as glaucoma surgery model
The eyes of NZ White rabbits were surgically opened and treated with different solutions. At intervals, some were killed to analyse the eye tissue.
Monitoring vital signs of rabbits during intercourse
NZ White rabbits were anaesthetised and implanted with devices to measure vital signs. They were then monitored during intercourse.
Harvesting rabbit caecum for lab tests
Domesticated rabbits were anaesthetised. Part of their digestive tract was removed, and then they were killed.