Temperature changes, such as those involved in heat and cold shocks , can induce heat shock protein 70 (HSP70) gene expression and stress responses in fish. This study observed the expression regulation of the HSP70 gene and the changes in plasma cortisol and glucose levels as a stress response in red-spotted (Epinephelus akaara) and hybrid (E. akaara female ×E. lanceolatus male) groupers during exposure to heat and cold shock. In red-spotted groupers, heat shock exposure did not induce upregulated expression of the HSP70 gene. This compares to a seven-fold increase in HSP70 gene expression, but it did trigger gradual increases in plasma cortisol and glucose as a stress response in both types of groupers. During cold shock exposure, HSP70 expression in red-spotted groupers almost doubled, but it was lower than that of the hybrid groupers . The hybrids exhibited gradual increases in HSP70 expression, nine times greater than that of the control group . HSP70 expression patterns of hybrid groupers were completely reflective of thermal stress responses of the fish. Although the effects of temperature stress on HSP70 expression in fish requires further study, the results of this study suggest that variations in HSP70 expression can serve as a sensitive biomarker of adaptation to temperature stress in specific fish.