Aquatic conditions of shrimp ponds developed in a mangrove area in the Mekong delta of Vietnam are investigated and the physical mechanisms that form their aquatic environments are discussed. The mangrove canopies play an important role in the stabilization of water temperature in the shrimp ponds through day and night At night, the dissolved oxygen concentration in the shrimp ponds is reduced to the survival limit for shrimps, but it recovers owing to the photosynthesis of phytoplankton in the shrimp ponds. On the other hand, the opening of a sluice gate supplies a lot of oxygen to the shrimp ponds from a tidal creek which connects to the open sea. Furthermore, the aquatic environment of the shrimp ponds depends on hydraulic processes such as the density flow which is formed by saline water supplied from the tidal creek and the water mixing which is caused by the compound configuration of the shrimp ponds developed in the mangrove area.