Zebrafish are unsung heroes of contemporary science. The humble tropical freshwater fish is an under-appreciated species that has helped scientists worldwide to make new discoveries and develop new technology.
Many Hongkongers keep zebrafish in aquariums, but they got a glimpse of their scientific significance when the Water Supplies Department deployed them as its latest tool for monitoring the quality of drinking water. Water authorities in other countries have put the 2.5 cm-long silvery fish to a similar use. But that is just one of many services zebrafish have performed for science and technology.
Last month, scientists at the University of Sheffield used zebrafish to achieve a breakthrough in treating epilepsy, discovering small molecules that may be used in anti-epileptic therapy.
In 2009, the fish helped an international team of scientists discover the secrets of drug addiction. The team created hundreds of mutant zebrafish that were not susceptible to amphetamines. The scientists' observations help identify a set of 139 genes that may make people susceptible to drug addiction.
In 2006, using zebrafish for tests, City University of Hong Kong researchers announced a finding that hypoxia could affect the sex development, sex differentiation and sex ratio of fish and possibly those of other animals.
The zebrafish is one of many species whose full genomes have been completely sequenced. Others include humans, pandas, silkworms, rice, malaria mosquitoes, honey bees, dogs, cats, fruit flies, chickens, mice, chimpanzees, potatoes and cannabis.
And now, the fish will be helping Hong Kong's Water Supplies Department to save HK$2 million a year on water monitoring.
"We treat them very well," Water Supplies Department chemist Thomson Tang Ki-lai said. "They have much more space [relative to their size] to swim around in than the average Hong Kong person has to live in."
The department is using the fish and a bacterium called Vibrio fischeri to monitor the city's drinking water and detect toxins.
Additional reporting by Alex Lo