Expression analysis of heat shock protein 70 (HSP70) gene in liver (a), anterior kidney (b), and spleen (c) tissues of rohu, Labeo rohita, during different time periods (h, hours post-challenge, d, days post-challenge) of Aeromonas hydrophila infection. Fold expression was calculated as 2−∆∆Cq. Control group (0 h post-challenge) was taken as the calibrator