So I have about 24 cats that i take care of, and 6 of them are fixed so far, but i plan on getting them all fixed by April. Only problem is that i noticed that there are about 6 black cats, and i cant tell which is which. Is there a way i can help identify each cat from far away? I was thinking have a collar put on every single one when i trap them to get fixed but since they're outdoors i fear that the collar can cause them problems. I'd really appreciate any recommendations