A Fisher cat will get through the 2x4 wire. 1" chicken wire is the way to go, but keep in mind that quality varies! The wire that we wrapped our tractor with started rotting after only two years, but the wire we fenced our quail aviary with (a different brand and different supplier) is still in amazing shape, and super strong! I know everybody says to use hardware cloth, and yes, it is more heavy-duty, but it's also way more expensive, but I've never had issues using chicken wire, only with the staples used to attach it (you need the hammer-in fencing staples, not the cable staples you buy for a staple gun).