Fish do not change their expressions, unlike humans, making it extremely difficult to know their stress level. However, evaluating the stress response of fish in continuous aquaculture is essential because of their sensitivity to stress. A wireless biosensor system has been developed to easily visualize the stress response by monitoring the glucose level as its indicator. However, the system had a limited range of applicable fish species. The implantation site of the sensor, the interstitial fluid of the eyeball, is hardly found in saltwater fish. In this study, we focused on the implantation of the sensor in abdominal interstitial fluid to expand its range of applicable species. First, we confirmed the presence of glucose in the implantation site and confirmed that the biosensor operated normally even after immersion in the fluid. We also attempted to immerse the biosensor in the abdominal cavity of Nile tilapia (Oreochromis niloticus), then monitored the stress responses. Next, we implanted the biosensor in the abdominal cavity of the saltwater fish horse mackerel (Trachurus japonicus) and obtained some corresponding results, thus demonstrating that the biosensor can also be used in saltwater fish, expanding its application.