Can I return a fish that's dead I bought last Saturday and they told me I can return it if their not eating or its dead

I don't have fish, but if they told you that you could return it then I would take it back and talk to them.

Yes i believe its within 48 hours

I believe you can to the store you got it at.

Im pretty sure they have a 7 day return policy but you might want to call and check

Yes. You just need your receipt.