This study evaluated the therapeutic efficacy of amoxicillin (AMX) or lincomycin (LCM) in starry flounders ( Platichthys stellatus ) infected with Streptococcus parauberis . Seventeen S. parauberis strains isolated from various regions of Korea were tested to determine the minimum inhibitory concentrations (MICs) of AMX and LCM. A representative strain (HFTC0091) was used for the experiments. Following bacterial infection, starry flounders were treated with either oral AMX (40 or 80 mg/kg/d for 7 days) or a single intramuscular (IM) injection of LCM (10 or 20 mg/kg). High‐dose treatments with both antibiotics resulted in significantly improved survival rates (96%–100% for AMX and 76%–96% for LCM) compared to nearly 100% mortality in the untreated controls. Serum biochemical analyses (glutamic oxaloacetic transaminase [GOT], glutamic pyruvic transaminase [GPT], and total protein [TP]) showed no significant toxicity; however, GOT and GPT levels were slightly decreased in the LCM‐treated group, indicating a potential anti‐inflammatory role of LCM, which warrants further investigation. This study demonstrates the effectiveness and safety of AMX and LCM in treating streptococcal infections in starry flounders and highlights the potential of the antibiotics as therapeutic agents in aquaculture. Future studies should investigate whether LCM modulates inflammatory pathways and elucidates the underlying molecular mechanisms in fish.

EHP causes hepatopancreatic microsporidiosis in shrimp, leading to growth retardation without notable mortality. To examine potential environmental carriers, farmed bivalves were collected near shrimp ponds in Korea and screened for EHP using nested PCR targeting the spore-wall-protein gene. DNA of EHP was mainly detected in gill and digestive tissues of oysters, scallops, mussels, and clams. Histopathology after 24 h immersion exposure confirmed spores within the intestinal epithelium of clams, indicating short-term invasion potential. These results suggest that bivalves can retain and mechanically transfer EHP spores through shared seawater between shrimp farms and surrounding areas. Considering the environmental persistence of EHP, continuous surveillance of local invertebrates is recommended to reduce the risk of EHP introduction and further spread in aquaculture systems.