My question is, could you please explain to me tosfos d"h H'i mesuchrussia denizysa asor lheduka
Daniel kadosh, New York, United States
Briefly, Tosfos quotes an argument between Rabeinu Tam and many other Rishonim whether or not Sechitah which is because of Libun applies to other liquids than water. Rabeinu Tam says it does not, and therefore the problem in our Gemara cannot be Sechitah which is due to Libun, but rather due to Sechitah which is because of Dash (see Ramban who explains Rabeinu Tam's opinin at length).
All the best,
Yaakov Montrose