This article introduces an online water quality monitoring system for aquaculture. Its data acquisition module collects water quality data through dissolved oxygen, temperature, turbidity, conductivity, and pH sensors. The data processing module uses specific algorithms to process the data, such as applying temperature compensation to conductivity readings to improve accuracy, and also filters, classifies, and stores the data. The data communication module employs the ESP8266 wireless communication module to achieve remote transmission. The monitoring center, through an APP, enables real-time remote monitoring and analysis of the data, and sends alerts when values exceed thresholds, thereby facilitating intelligent aquaculture for farmers.