FIRST CASE STUDY OF COINFECTION OF Staphylococcus epidermidis AND Pseudomonas putida IN ANGELFISH (Pterophyllum scalare) IN SOUTH KALIMANTAN, INDONESIA, WITH THE MAIN CLINICAL SYMPTOM OF LETHARGY

Abstract

Angelfish (Pterophyllum scalare) is a freshwater ornamental fish with high economic value and intensive trade, which increases its susceptibility to infectious diseases. This study reports the first documented case of co-infection by Pseudomonas putida and Staphylococcus epidermidis in angelfish cultured in an aquarium in South Kalimantan, Indonesia. Mortality was recorded in September 2022 and occurred exclusively among angelfish exhibiting lethargy, darkened body coloration, abnormal swimming, and bottom-remaining behavior. Five moribund fish were subjected to clinical examination, post-mortem analysis, bacterial isolation, Gram staining, VITEK 2 Compact identification, and histopathological evaluation of eye and brain tissues. Bacterial isolation revealed P. putida from liver samples and S. epidermidis from blood samples. Histopathological findings showed severe cerebellar lesions, including spongiosis, Purkinje cell necrosis, granular layer degeneration, hemorrhage, and bacterial infiltration. Ocular lesions were characterized by cataract formation and bacterial presence within the lens. These findings indicate a systemic bacterial infection with central nervous system involvement. The results suggest that P. putida is the primary pathogen, while S. epidermidis acts as an opportunistic co-infecting bacterium. This report emphasizes the importance of comprehensive diagnostic approaches for mixed bacterial infections in ornamental fish to support effective disease management in aquaculture.