Cadmium is a highly toxic heavy metal known for its persistence and bioaccumulative nature. Aquatic ecosystems play a vital role in supporting diverse forms of life and maintaining ecological balance. It enters aquatic environments through a range of sources, such as industrial discharges, mining activities, and the use of Cd-based products. The Mozambique tilapia was exposed to cadmium for 4 months. After that, the gut stool was collected for 16s rDNA sequencing. The aim of this study was to understand the mechanisms of cadmium toxicity to the health of the fish gut. The results revealed that the low concentration of cadmium was also highly toxic to fish health.