chinatown fish

Question

Hi Rabbi, Is fish from chinatown kosher? Specifically, is there a difference if one buys whole fish or sliced up fish from there? (Considering that the sliced may be laying on the ice adjacent to squid, etc.) Does it matter if they slice a whole fish for me with their utensils? Thanks! Shabbat Shalom. (p.s., sorry if this is duplicated, but I did not see the first post hit the board.)