i've never had duck fat go bad in my fridge. beyond 4 nor 5 months, i wouldn't know, as it usually doesn't last longer than that. besides using it to fry potatoes and other veggies, i like to spread duck fat on rye bread for a tasty snack. i'm not a proponent of straining duck fat, though. i save as much of the brown ducky bits of fond as i can. the fond settles to the bottom of the fat container. invariably, i find myself digging down into the duck fat tub with my knife to get to those delicious, salty little duck bits every time....