Seasonal fishing bans will be imposed on the Pearl River and the middle and lower reaches of the Yangtze River in April.
The move is part of China's efforts to rescue its declining wild fishing resources, and is in addition to bans in six other provinces and regions.
A 2-month ban will cover the 2,400-kilometer Pearl River, China's third-longest river, as well as its tributaries and some lakes.
Meanwhile, a 3-month ban will affect the middle and lower reaches of the Yangtze River, from Gezhouba Dam in Hubei province to Shanghai's Chongming Island.
Fishing is usually banned in the upper reaches of the river annually from February to the end of April.
The ban is the 11th annual attempt to preserve biodiversity in the country's longest river, home to 1,100 aquatic species and to two-thirds of those on the list of protected wildlife .
Liu Tianrong, deputy director of the South China Sea Fishery Bureau, said on Tuesday that the ban on the Pearl River last year greatly helped improve fish varieties and increased fishermen's income after the ban.
For example, the number of newly hatched fish in the Pearl River increased by 67.5 percent in 2011 from 2006, he said at a news conference in Guangzhou.
Last year, more than 29 million newly-hatched fish were put into the river during the ban.
Local civil affairs bureaus will provide subsidies to fishermen with low incomes during the ban.
Last year, more than 28,000 fishing boats and over 114,000 fishermen were affected by the ban.
But the number of some well-known species in the Yangtze River is still declining by 5 percent annually.
China has experienced a rapid growth in its fishery industry in recent years, with increasing aquatic product output and prices, as well as soaring exports.
The country's exports of aquatic products reached $17.8 billion last year, accounting for nearly 30 percent of its total agricultural product exports.
But experts believed fishery harvests now greatly rely on the booming captive breeding, as the country's wild fishing resources are declining.