-δ subunit). The full-length cDNA of this gene was cloned by rapid amplification of cDNA ends (RACE) PCR, and the expression of this gene was detected in different tissues by semi-quantitative RT-PCR. We then measured the relative expression of this gene in the different tissues following exposure to acute hypoxia stress of mg/L, 3.37 , or 0.54 mg/L dissolved oxygen [DO] using quantitative real-time PCR. The full-length cDNA of the mitochondrial ATPase subunit gene was 762 bp, containing an open frame reading of 480 bp encoding 159 amino acids, and a 114 bp 5-untranslated region. The deduced amino acid sequence of the mitochondrial ATPase (89%) and moderate similarity with Oncorhynchus masou formosanus(74%), and (69%). Expression of the gene was highest in the heart followed by the muscle, with low levels of expression in the brain, liver, and spleen in silver carp. Expression of this gene decreased gradually as dissolved oxygen levels decreased. Expression in the heart was significantly lower (0.05) in the hypoxia-exposed fish than in the control group. Conversely, levels were initially significantly higher (<0.05) in the brain, liver, spleen, and muscle of hypoxia-exposed fish, before decreasing significantly (<0.05). -ATPase activity first increased then decreased in all the tissues during acute hypoxia stress. Changes in expression of the were consistent with changes in ATP enzyme activity in the brain, liver, spleen, and muscle, but not in the heart. The initial increase in expression of changes in desolved oxygen(DO). However, if damage to the inner mitochondrial membrane leads to loss of self-regulation when DO becomes too low, expression will rapidly decrease. This disrupts energy metabolism and blocks energy synthesis. Oursubunitgene may play a role in the response to hypoxia stress and influence the production and activity of ATPase in silver carp.