Plastic keeps the fish smell. Go glass.

Plastic lunch boxes will always hold onto fish curry odors—your best fix is to switch to glass or stainless steel.

For the container you already have, try the hard stuff: a thick paste of baking soda and water all over the inside, left overnight. Or fill it with hot water and a big splash of white vinegar, seal it, and let it sit for a few hours. Then wash it and put it in direct sunlight for a day. Sunlight genuinely kills a lot of the stink. But I’ll be honest: if that curry sat for a week in there, the plastic is probably permanently flavored. Toss it if it still smells after two rounds.

The real solution is to stop using plastic for anything spicy or oily. Glass and stainless steel don’t absorb odors at all. Ceramic is also great. Silicone is better than plastic but can still pick up smells, especially if it’s cheap silicone. For curry, I’d go glass with a leak-proof lid—it just rinses out clean and never haunts you later.

This is one of those cases where the fix is a two-dollar upgrade. Your future lunches will thank you.