The Taiwan Ku Fish

There's a saying in Taiwan's Tainan and Hualien Counties that goes, "Rich, eat ku fish; poor, eat eel." Ku fish, a prized catch of local fishermen, is actually native in all the world to only a few places in Taiwan and was discovered just 60-some years ago.

That was in 1920. The Japanese who discovered the fish gave it a Japanese name, oshima, and a Latin one, Varicorhinus alticorpus, classifying it under the genus Cyprinidae. It was not until 1954 that it acquired its formal name in Chinese, the "tall-body" ku fish.

The first person in the world to systematically study the fish's habits and habitat may well be Tseng Ch'ing-hsien of the National Taiwan Science Educational Hall in Taipei. An expert on Taiwan's freshwater fish, he paid little attention to the ku fish until three or four years ago, when environmental questions began to draw notice in Taiwan and the fish's status as an indigenous species attracted his interest.

Of the 150 species of fish native to Taiwan, a dozen or so are found nowhere else in the world, among them the rare ku fish. The ku fish inhabits the middle reaches of Kaoping River in western Taiwan and portions of the Peinan, Hualien, and Hsiukuluan Rivers in the East. And its tasty flavor makes it a precious catch.

The ku fish prefers to live in clear, rapidly flowing mountain streams below 1,000 meters in altitude at temperatures between 15℃. and 25℃.

Although Taiwan's freshwater fish, unlike most fish found at tropical latitudes, are not particularly fetching in appearance, the ku fish is quite pretty. Some people have called it "a silvery exclamation mark."

Living in the swift currents and rocky beds of torrential mountain streams, the ku fish has developed agile movements and superb swimming skills. As it darts about, shining with silver-white scales, among the cracks and crevices of its home, it does indeed resemble an energy-charged "exclamation point."

During the mating season, from about July to October, adult female ku fish become lovely "blushing" brides, as a pink flush spreads out from under their gills and fins and over their stomachs.

"The function of the 'wedding blush' is to attract the attention of the opposite sex," Tseng Ch'ing-hsien explains, pointing out that the color gradually disappears once the mating season is over.

A discussion of the ku fish could scarcely omit mention of its close relative, the k'uhua fish. K'uhua live in colder water, below 20℃., are more adaptable and widespread, and represent a more primitive species than the ku fish. Both kinds of fish look quite similar in appearance to guppies, but as they grow older the k'uhua keeps its slim figure while the ku fish fills out, achieving a height (measured from the dorsal fin to the stomach) 1.5 times that of the k'uhua. The ku fish can also be distinguished by its smaller eyes and lack of whiskers.

The most characteristic feature of the ku fish, however, is its mouth. The mouths of most fish are right on the front tip of their heads, but that of the ku fish's is located underneath, and is broad and crescent shaped. Its lower jaw has a sharp layer of cuticle, which it uses in feeding, scraping algae and insects off underwater rocks.

"Blessed" with tender, tasty meat, the ku fish is a prime target of fishermen. "Ten years ago you could easily catch 11 or 12 kilos of them in their breeding grounds," Tseng says. But with the introduction of large-scale fish-killing techniques like electrocution, poisoning, and dynamiting, ku fish numbers have been declining drastically.

At the same time, environmental changes are shrinking their living space. Says Tseng: "Silt and sediment from the upper reaches of Hualien River has produced a sharp decline in the river's animal and plant life. On top of this, the waste water discharged from nearby factories has polluted the river and raised the water temperature, so there are a lot fewer ku fish there now."

A ku fish requires two to three years' time to grow from an egg to a mature adult, while artificial cultivation would demand a considerable investment.

Never thriving to begin with, pressed by Man's encroachments, "how can the ku fish be adequately protected and kept from changing from a 'rare' to an 'endangered' species?" Tseng Ch'ing-hsien anxiously asks.

If the ku fish has a consciousness, it's probably anxious, too.