Can I purchase kosher fish from a non-kosher store?

am I allowed to purchase Kosher fish from a non- Kosher fish store can there's two things you have to keep in mind one is confirming that the fish itself was kosher before it gets cut out and two to make sure that it maintains its kosher status as it's cut up in order to know that fish is kosher you have to check that it has scales that can be removed without ripping the skin you could try to remove a scale yourself or you can have the worker try to remove the scale in your presence to make sure that it comes off of the skin and the skin remains intact once you've determined the fish's kosher you also have to make sure it's cut up in a Kosher Way that means that the knife the board the gloves and any other equipment that your fish makes contact with has to be clean that would mean asking the worker to change their gloves check that the knife is washed cover the board Etc and making sure that the fish came directly from a manufacturer shipping box assuming you did all of those things then you would know that your fish was 100% kosher as soon it was finished you had no concerns at all you could just use it as is that isn't always possible if the worker handled the fish already before you got there or the fish wasn't able to come directly out of a box as long as you still checked that the scales are either intact and removed in front of you or could be removed without ripping the skin and the skin is still on the fish only concern that you had at this point is the way it was handled that maybe some non- cusher residue touch the fish here's how you would fix that you would take it home you would rinse it in cold meaning not hot water then you would scrape it with a non-s serrated sharp straight edge knife using a little bit of pressure maybe a little bit more than a little bit but just enough to scrape every surface of the fish in order to scrape off any non-er residue that might be stuck on the fish then you rinse it all off after you did that both your fish and your knife and your sink would all be kosher