Gamma-aminobutyric acid (GABA) is a neurotransmitter that exerts several physiological functions and positive effects on human health. The aim of this study was to isolate and characterize the strains that had GABA-producing abilities from various fermented fish products. A total of 91 acid-producing strains were isolated from 41 samples of fermented fish products, and 27 strains showing GABA-producing abilities were identified by the 16S rDNA sequences. Among the strains, 31% strains tolerated at high-salt environment of 10-20% throughout the fermentation of fish sauces. The 27 isolates that produced GABA at various concentrations did so in the range of 5 to 454 mM. These GABA-producing isolates were identified as lactic acid bacteria of 14 strains, which included twelve Lactococcus lactis, one Enterococcus faecium, and one Lactococcus pentosus; eight Bacillus cereus group, which included seven B. thuringiensis and one B. cereus; and five Staphylococcus spp. Interestingly, with Vietnamese fish sauces, we mostly identified species of B. thuringiensis and Staphylococcus spp., while with Korean fermented fish products, the majority of the strains identified belonged to L. lactis. Among the strains, B. thuringiensis LH2134 produced the highest levels of GABA at 366 mM among the strains identified from Vietnamese fish sauces, whereas L. lactis LA43, a new strain isolated from Korean jeotgal (salted shrimp paste), produced the highest amount of GABA at 454 mM and the glutamate concentration in the medium was essential for GABA accumulation. Therefore, such the isolates might serve as good starters for development of more GABA-reinforced foods among fermented fish products. 210 Vo and Park J. Microbiol. Biotechnol.decarboxylase, whose biochemical properties have been reported previously [3]. GABA is served as a bioactive compound in foods and is seen as a great bioactive natural compound for human health since it exerts several physiological functions and also has positive antioxidant, anti-diabetes, hypotensive, and anxiety reduction effects [4]. GABA could delay or inhibit the invasion and metastasis of various types of cancer cells in the mammary gland, colon, and hepatic cancer cells [5]. Indeed, GABAenriched food is required because the GABA content in the typical daily human diet is relatively low [6]. As a result, the development of functional foods containing GABA has been actively increased with a vast variety of GABAenhanced food products including cereals, sourdough, breads, cheeses, fermented sausages, teas, vegetables, legumes, dairy soy products, alcohol beverages, and especially traditional Asian fermented foods [7].A high amount of GABA is found mainly in fermented products, especially fermented dairy products [8]. GABA produced by fermentation with microorganisms has been reported in bacteria, fungi, and yeasts [9]. The most interesting and practical group of bacteria for GABA production is lactic acid bacteria (LAB), including strains of Lactobacillus (L.), and Lactococcus (Lc.), of which L. brevis wa...