This study was carried out to isolate, identify and determine the pathogenicity of the fungus Fusarium incarnatum-equiseti, which was isolated from swollen swim bladder of striped catfish (Pangasianodon hypophthalmus) cultured in Viet Nam. The typical sign of swollen of the swim bladder was observed. The fungus was identified based on morphological characteristics and molecular phylogenic analyses with a partial sequence of the elongation factor-1α (EF-1α) gene of fungal isolates. A challenge test of F. incarnatum-equiseti to striped catfish using a selected isolate was also implemented and the results showed a similarity to those of naturally infected fish. Histopathologically, the signs of hemorrhage, vacuolar degeneration and necrosis and the presence of fungal hyphae and conidia were found in the in the sinus of swim bladder. The result confirmed that F. incarnatum-equiseti was isolated and pathogenic to striped catfish. This is the first report of a fungal infection found in striped catfish inViet Nam.