Baking soda is the lunch box answer.

To keep lunch boxes from smelling like yesterday’s fish, the trick is washing them quickly and using baking soda for the stubborn spots.

Fish smell sticks because the oils cling to plastic and linger long after the food is gone. The fix is simple: wash the lunch box as soon as you get home, not tomorrow morning. Hot, soapy water does most of the work. For plastic containers that still smell, fill them with warm water and a hefty spoonful of baking soda and let them soak overnight. Rinse well and let them dry completely in the sun if you can. Sunlight kills the odor naturally.

If you’re packing fish again, do yourself a favor and keep it in a separate sealed container inside the lunch box, not loose. That way the box doesn’t absorb the smell in the first place. And no, fancy sprays or scented liners aren’t better than the basics — they just cover one smell with another.

This is not where you save six bucks on a new lunch box. Do the soak.