Ah, yes. The Fiddy. This watch is a beast. You need 26mm straps for it. Since you didn't mention a price range I'll just throw out my two favorite strap makers knowing that they might be a bit expensive for your tastes...
http://www.vintagerstraps.com - The guy's name is Micah and his straps are incredible. Easily the softest straps I own, and yet also among the thickest (a desirable quality to me). I have a Copperplate and a Carrier. They're both fantastic and would look great on a Fiddy.
http://gregstraps.blogspot.com - The guy's name is Greg Stevens. Probably the most popular strap in Paneristi land right now. I have a Crazy Horse and have a black on my wishlist. Greg straps, IMO, are second to none. The Crazy Horse is my work horse strap.
On the low end, you can look up BOB and DON straps. Lower quality, lower price.
Enjoy. Straps are as big an addiction as PAMs themselves... Maybe bigger.