The sudden and absolute downfall of Pharaoh and his army is captured through a vivid image of fish violently uprooted from their natural habitat and cast onto the dry desert floor. By severing them from the Nile, which serves as their life source, their immediate destruction is guaranteed. The act of casting them out represents a total scattering and abandonment [מצודת ציון, ביאור שטיינזלץ]. The harsh desert environment completes the picture. Just as aquatic creatures instantly perish when thrown onto dry land, the Egyptian forces face complete annihilation [רש״י, רד״ק, צאינה וראינה].
Beyond the striking imagery, the practical reality of this prophecy is a devastating military defeat. The Egyptian military will be completely scattered. Rather than taking a defensive stand from within the safety of their fortified cities, they will march out into the open field to engage the Chaldeans in battle, where they will ultimately fall by the sword [מלבי״ם, רד״ק]. During this open conflict, they will meet their end entirely exposed [מצודת דוד, ביאור שטיינזלץ].
The aftermath of the battle will bring an especially harsh fate for the fallen soldiers. There is a general consensus among commentators that the Egyptian dead will be denied a proper burial, left abandoned where they fall. Drawing upon the fisherman metaphor, a precise distinction is made regarding how bodies are normally handled. Typically, a fisherman first sweeps his catch together into one place before collecting them to bring inside. In this devastating defeat, the bodies of the Egyptian soldiers will not only be denied the dignity of being collected for a proper burial, but they will not even be gathered together on the battlefield. Instead, they will be left utterly forsaken, serving only as food for roaming beasts and scavenging birds [מלבי״ם].