Abstract
Rotation farming of rice and shrimp is a typical farming system in the Mekong Delta of Vietnam, where saline water intrusion takes place seasonally. In this area, shrimp (Penaeus monodon) culture is carried out during the dry season and rice is cultivated during the rainy season. The growth, survival rate, water quality variation and cost: benefit ratio of the system were monitored in three experimental shrimp farms (1-1.3 ha per pond) in Soc Trang province and three others (0.4-0.5 ha per pond) in Bac Lieu province. The water quality did not vary much; the growth rate was 0.23 to 0.29 g day-1, average survival rate reached 89%, average shrimp yield was 392 kg ha -1 and the cost: benefit ratio was 1:4.6 to 4.8. However, white spot syndrome virus (WSSV) occurred in the farming system, especially in seasonal transition (dry and wet season).