"Businessmen fish in troubled waters," muses Robert Kuok Hock Nien, the Malaysian tycoon whose China investments run to billions of dollars.

"When the sea looks calm, you are unlikely to catch any fish."Mr. Kuok should know.

He opened Beijing's World Trade Center, two hotels and two luxury apartment blocks in 1990, not long after the uncompleted structures were strafed with gunfire in the 1989 anti-democracy Tiananmen Square massacre.

Through the winter of 1990-91, the apartments and offices were empty, and rooms in the five-star China World Hotel went for $30 a night.

These days, a room costs $240 a night, a three-bed apartment costs $6,000 a month, and the World Trade Center is the most expensive office space in the country, at $90 to $120 a square meter (10 square feet) a month.

Since the launch of China's anti-inflation austerity program last year, the economic waters have begun to look choppy again, creating a business environment in which hardship and opportunity are once more familiar rivals.

Credit is tighter than it has been for years and China's ailing state sector is feeling the pinch.

For the past 18 months, between one-third and one-half of medium-sized and large state enterprises have reported losses.

Overall losses for 1994 were officially 33.6 billion yuan ($4.1 billion). Far more red ink is believed to be hidden in the books of China's banks, whose government-mandated loans to state firms are not being repaid.

In July, the official China Daily newspaper quoted estimates from the State Council's Development and Research Center saying 20 million of 120 million surplus workers in the state sector have been laid off this year.

The figures are impossible to confirm but prima facie evidence - rising numbers of beggars on the streets of industrial cities - suggests life for people is hard.

One man's misfortune, however, is another's opening.

The private sector is cutting costs as office rentals fall, the yuan appreciates and slowing inflation takes the heat out of wage settlements.

Exports in the first seven months of the year were up 40 percent, to $82 billion. Retail price inflation dipped, to 12.3 percent, in August. Prime office rents in Shanghai and Guangzhou have dropped by around one-third; Beijing is expected to follow suit.

Foreign investors are seeing opportunities, too. For many, the domestic credit crunch has strengthened their bargaining positions. "Our Chinese partners are strapped for cash," said the Shanghai-based manager of a European multinational with half a dozen joint ventures in Beijing, Shanghai and Guangzhou.

"In several cases, the situation has allowed us to inject new funds in return for greater control. We're consolidating our position."

In southern Guangdong province, Hong Kong-listed Wai Kee Holdings teamed up with American International Group Inc., the New York-based insurance giant, to bankroll five toll road projects that were running out of money.

The deals, covering 135 miles of new highways, give the foreign investors minimum profit guarantees and preferential profit distribution.

The average pay-back period on the projects is assessed by Hong Kong brokerage Peregrine at six years against contract terms of 15 to 30 years.

Those are not the kind of terms that investors were getting at the height of China euphoria in 1992 and 1993.

"We're entering a new phase in the investment game," said the Shanghai- based manager. "From the outside it looks tough, but personally I think it's good for business."

Mr. Kuok, whose companies bottle Coca Cola in China, operates the country's leading luxury hotel chain, Shangri-La, and trades billions of dollars of edible oil and other commodities each year. He is not alone in his fondness for stormy waters.