Abstract Background Cutaneous infections are important diseases in captive and free‐ranging pinnipeds and are associated with various causative agents. Some special agents, such as fungi, morbillivirus and mycobacteria, can cause cutaneous specific granulomatous inflammation. Objectives To identity the cause of chronic dermatitis in a spotted seal in an aquarium. Methods Herein, we analyze the clinical history and cutaneous samples of the spotted seal through differential diagnosis (histopathology, microorganism culture, special histochemical staining methods, PCR), and antibiotic susceptibility test. Results This is a rare pyogranulomatous dermatitis case caused by E. faecalis in a captive adult male spotted seal ( Phoca largha ) in an aquarium. Conclusions We provide a meaningful approach to the diagnosis and treatment of bacterial dermatitis in pinnipeds.