דברים, פרק י״ד, פסוק י׳

The dietary laws regarding aquatic life establish clear boundaries for what may be consumed. The restriction against eating aquatic creatures lacking fins and scales extends far beyond ordinary fish. The rule encompasses absolutely every living creature found in the water, including swarming water insects and any other aquatic life [ביאור יש״ר, ביאור שטיינזלץ].

The impure status assigned to these forbidden creatures does not refer to actual ritual impurity. Coming into contact with dead fish does not make a person impure. Rather, the impurity simply means that eating these creatures is considered disgusting and entirely rejected [חזקוני].

Furthermore, the transition from the laws of impure aquatic life to the laws of birds reveals a completely different restriction. This specific sequence teaches that it is forbidden to eat the live bird that is set free during the purification process of a person recovering from a severe skin disease [קיצור בעל הטורים].