Fish is one of the primary sources of food that human beings can consume. With that idea, this study aims to monitor fish quality by monitoring specific parameters to keep track of fish’s safety levels, which are unnoticeable to the naked eye. This study focuses on helping cafeteria owners be more observant of the quality of fish they are serving their customers. A mobile application is developed through the MIT App inventor to have a user-friendly system that can aid users in quickly identifying the data transmitted from the device using the internet. With the help of the Rapid Application Development (RAD) process model, the researchers were able to implement the concept of the fish quality monitoring system. The Arduino Wemos D1 R1 development board acts as the main component of the device. The built-in ESP8266 Wi-Fi module in the microcontroller allows data transmission from the device to the ThingSpeak application, which acts as the system's online database. The process of how the system works is that the MLX90614, MQ4, and MQ137 sensors gather the Temperature, Methane, and Ammonia gas measurements. Once the device has processed all the data, the outputs can be displayed on the mobile application so that the user can decide if they still want to check the output graph.