Rare HK fish faces danger in paradise

PUBLISHED : Monday, 31 October, 2011, 12:00am
UPDATED : Monday, 31 October, 2011, 12:00am


The only freshwater fish named after Hong Kong, identified recently as a new species, is already dwindling in numbers, spurring efforts by scientists to step up a breeding programme.

The Hong Kong paradise fish, Macropodus hongkongensis, found only in the city, is threatened by man-made damage to its habitat.

Researchers are now examining its genetic make-up with a view to aiding the government's breeding programme.

Last year, Chinese University obtained funding of HK$854,440 from the Environment Conservation Fund for a three-year study to see if there are genetic differences within species of fish found in different parts of Hong Kong.

Six species are being studied, including two that are of conservation concern - the Hong Kong paradise fish and the rice fish, Oryzias curvinotus.

'Animals in the ocean or on land can go anywhere they like, but this is not the case for freshwater fishes in streams,' Tsang Ling-ming, a post-doctoral fellow at the university, said.

'You can have two streams that are very close together, but the water may be from different sources; the water could be different in temperature or pH level, which means one gene pool of fish may survive in one stream but not the other.'

The Hong Kong paradise fish is the only fish that breeds by attaching its eggs to bubbles and then stays with the eggs - an uncommon habit, because most parent fish will leave their offspring to fend for themselves.

The fish can be found only in Tai Po, Sai Kung and parts of the New Territories where the land is not too hilly, so that the currents in the streams are more gentle.

The Agriculture, Fisheries and Conservation Department has listed so far 21 fish species as requiring conservation.

Tony Chan King-tung, a nature conservation officer with the department, said it was important to protect the genes of the fish, because they will determine whether newly bred fishes under the breeding programme will survive when they are reintroduced into a freshwater environment.

'One species of fish may still have genetic differences,' Chan said.

'They adjust to the place where they live, and some fishes may have adjusted to more sunlight or a faster water current, and their bodies will become adapted to the environment over generations.'

It was therefore important to record the genetic information of the fishes found in each location, Chan said. 'We definitely do not want fishes with different genes but of the same species mixing together in their habitats, because that may weaken their ability to adjust.'