We found a cat. Advice?

Cute adorable black kitten, we found meowing at our door. Very friendly, gets along great with our dog. Has claws but as far as I can tell it doesn’t have any parasites or even fleas. So while I wait till tomorrow to try to find its owners (even if I don’t want to) I’ve decided to take care of it for tonight at least.

So my cat got run over a few months ago and since then I’ve thrown away her litter boxes, but I kept a portion of her food. It looks too large for the cat to eat. I also have coy fish food (for my turtles) but I’m not sure it is good for the cat to eat that. The cat looks really thin, but I don’t remember what my cat looked like when I got her as a kitty so it might be normal.

Either way, anyone have any advice on what to feed or care for it for the night, or a method to find the owners? I don’t really want to go door to door, but I will if I have to. The cat doesn’t have a collar.