Bleach and baking soda will fix a fishy cooler.

A diluted bleach solution followed by a baking soda paste does the job. You don’t need a fancy cooler cleaner or a new cooler.

The fish smell comes from bacteria and oils. Bleach kills the bacteria. Mix one tablespoon of bleach per gallon of water, scrub every surface, let it sit for ten minutes, then rinse thoroughly. Don’t use more bleach – you’re not sanitizing a hospital.

After that, make a paste of baking soda and water and coat the inside. Let it sit overnight or at least a few hours. Baking soda is a slow but reliable odor absorber. Rinse again in the morning.

If the smell lingers, leave the cooler open in direct sunlight for a day. UV light breaks down odor molecules. Combined, these steps work on even the oldest fish cooler.

Your cooler will smell like a cooler again, not a bait shop.