Kosher Fish Signs and Treifah Status of Needle in Kurkavan

Description

The Chasam Sofer corrects two misunderstandings: he clarifies that fins enable surface swimming while scales indicate non-toxicity, decisively rejecting the analogy between an undeveloped fish and a chick whose eyes have not opened, since a fish's species status is fixed from birth. On the kurkavan question, he endorses the Radbaz's critique of the Rashba's ruling that a needle stuck from outside renders the animal treif, while adding that the Radbaz's own position regarding checking internal organs when a thorn perforates to the body cavity is itself questionable based on Rashi in Chullin 53b.