In this study, we explored the correlation between the lysosome–mitochondrial apoptosis pathway and fish softening, as well as the correlation between ferritin degradation and lysosomal iron changes. The results indicated that ferritin levels gradually decreased, lysosomal iron first increased and then decreased and tended to stabilize, and lysosomal membrane stability significantly decreased (p < 0.05). Spearman’s analysis suggested that an increase in lysosomal iron was associated with ferritin degradation. Lysosomal instability promoted the release of cathepsin D, thereby increasing the release of Bid and Bax, and inhibiting the expression of Bcl-2. Subsequently, caspase-9/􀀀 3 was activated. In addition, transmission electron microscopy revealed ultrastructural

damage to mitochondria and cell nuclei, which are morphological features of apoptosis during post-mortem storage. Moreover, TUNEL staining confirmed the occurrence of apoptosis. We concluded that the lysosome–mitochondrial apoptosis pathway was active during the storage of Esox Lucius, in which ferritin degradation and increased lysosomal iron were key factors inducing lysosomal damage, and cathepsin D released by lysosomes was a key factor connecting lysosomes and mitochondria.