Salinity and water temperature are parameters that can affect the life of aquatic biota because salinity and water temperature influence osmotic pressure. To stabilize the life of aquatic biota from osmotic pressure tolerance, controlling the values of salinity and temperature is necessary. This research aims to design a stabilizer and monitoring system for salinity and temperature in water. The system developed from this tool uses a salinity sensor to detect salinity levels and a DS18B20 temperature sensor to detect the water temperature, then the ESP01 sends the sensor reading data to the thinkspeak database for storage and real-time display, while Arduino Uno serves as the microcontroller. The results of the study show that the tool can detect and stabilize the salinity and temperature of the water according to the ideal value data for Catfish with a salinity reading of 3.1 ppt and water temperature of 25.5℃, and for Goldfish with a salinity reading of 4.6 ppt and temperature of 26.87℃.