תהלים, פרק ק״ה, פסוק כ״ט

The historical account of the plagues striking Egypt begins directly with the transformation of the nation's water sources into blood by God [ביאור שטיינזלץ]. The narrative deliberately skips the earlier event where a staff turned into a serpent, as that was merely a preliminary sign rather than an actual plague [אבן עזרא].

The transformation of the water is closely tied to its immediate and devastating result: the death of the fish. This connection highlights the absolute and sudden nature of the change. Because fish can only survive in water, the exact moment their environment became blood, they died instantly [מאירי].

Beyond simply recording the damage, the death of the fish served a crucial purpose in proving the reality of the event. The Egyptians were deeply skeptical and might have dismissed the plague as a mere optical illusion or an act of local witchcraft, which would have fueled their refusal to free the Israelites. However, the dead fish provided undeniable proof. It showed definitively that the water had not just taken on the appearance of blood, but had physically changed into actual blood. From the very first strike, this physical evidence made it clear to the Egyptians that they were facing the true power of divine providence rather than the tricks of sorcerers [אלשיך].