A premium koi food sitting open for 6 months loses most of its vitamin content. Storage matters.
Sealed and Cool
Vacuum-sealed in original bag, stored in a cool, dark place. Vitamin C drops ~30%/month in heat and light.
Buy in Quantity Wisely
Don't buy more than a 3-month supply at once. Bulk savings disappear if half the bag degrades.
Freezer for Reserves
Long-term storage of high-quality food: freezer in airtight container. Pull out and thaw 2 weeks of food at a time.
Smell Test
Fresh food smells slightly fishy/grainy. Rancid food smells sharp or sour. Throw it out.