The Arowana fish cultivation is a special cultivation that grows decorative fish instead of consumption. Unlike consumption fish, Arowana fish require a strict water pH level to live healthily. Hence, the cultivator must carefully maintain the water to prevent high acidity levels in the aquarium. A high acid level in the water may cause severe disease or death to Arowana. However, detecting acidity levels in the water required a particular tool, such as litmus paper. Litmus paper provided accurate acid detection by color indication. A strip of litmus paper is required for every aquarium to detect the acidity level. Buying many litmus papers may increase the unnecessary cost of cultivation. This research proposed acidity level monitoring by implementing Internet of Things technology to allow automation and remote monitoring. According to the evaluation result, the proposed model is capable of detecting the state of the acidity level with an accuracy of up to 100%. Besides that, the detection range of the proposed model is almost identical to a pH meter with a percentage error of less than 1% in many acidity levels.