The Mekong River Delta is a key area for aquaculture production, providing over 66% of Vietnam’s  aquaculture production annually. However, large-scale cultivation and intensive farming have resulted in deterioration of aquaculture water quality and higher rate of aquatic animal diseases. Therefore, water quality control is the key to succeed an aquaculture management. This work presents the design and deployment of an IoT-based water quality monitoring system for Pangasius fish farming in Mekong Delta. The designed system allows farmers to monitor in real time the most important physico-chemical variables of the pond water. Especially, this work introduces a simple and effective approach for automatic cleaning sensor probes that helps improve sensor readings reliability and reduce maintenance costs.