Design and Implementation of a Low-Power, Real-Time, Water Quality Monitoring System for Fish Transport

Live fish transport poses significant challenges for aquaculture, particularly in maintaining optimal water quality during transit. This thesis presents the design and implementation of a lightweight, low-power, real-time monitoring system for use in mobile fish transport tanks. The system continuously measures critical parameters: dissolved oxygen, temperature, and turbidity which are key indicators of fish health and stress. The hardware integrates commercial optical and nephelometric sensors with a Nordic nRF52832 Bluetooth Low Energy (BLE) microcontroller. Sensor data is transmitted wirelessly via a browser-based Web Bluetooth interface and displayed locally on an LCD. Visual and audible alerts are triggered when parameters exceed safe thresholds. A UART multiplexer enables interfacing both RS-232 and RS-485 sensors through a shared UART port, reducing hardware complexity. Although full dual-sensor integration was limited by the oxygen sensor’s automatic mode, the architecture supports polling-based operation and was validated with each sensor independently. Powered by a 2800 mAh Li-ion battery, the system achieved a runtime of approximately 6 days. Controlled testing using simulated contamination (milk and carbonated water) confirmed system responsiveness and reliability. The results demonstrate a scalable and low maintenance solution for enhancing fish welfare during transport, with potential applications across aquaculture and environmental monitoring.