The swelling phenomenon of packages containing Mamakari fish treated with vinegar seasoning was observed. Analysis of the swollen sample revealed lactic acid bacteria but not in a normal sample, and the isolate was identified as Lactobacillus brevis. The process of carbon dioxide gas production was supposed by heterofermentation and glutamate decarboxylation. Growth of the isolate was inhibited additively in a mixed solution containing acetic acid, lactic acid and NaCl. Accordingly, it is shown that growth of the isolate causing swelling of the package was inhibited by vinegar seasoning containing appropriate organic acid contents.