We are often asked the question if we supply expired koi food at cheaper prices? Even though we understand that koi food can be expensive and when having to feed 5kg per day can work out to a substantial sum of money, the short answer is no. It can lead to malnutrition, poor water quality and in some cases may even kill your koi.
Even though there are no industry recognised standards for shelf life, studies have been done and a reasonable estimate for the shelf life of dry pet foods (e.g. dog/cat kibble, fish pellets, etc) is 12-18 months, depending on the antioxidants used and storage conditions. Shelf life in the pet food industry is usually determined through chemical analysis of oxidation products, palatability testing, and olfaction. The main cause of diminished shelf life in dry products is oxidation. This not only causes rancid odours and alters flavour reducing palatability, but also destroys essential fatty acids and the fat soluble vitamins A, D, E, and K potentially leading to malnutrition in your koi. It is best to stick with non-expired food so as to avoid having to supplement for the lost nutrients, reduced palatability and potentially destroying the clarity of your water.
While nutrient loss will be a certainty, the overall quality, and even safety of the food, will depend on a number of factors. There is always a risk when dealing with foods that contain high fat content (fat will go rancid over time) and/or high moisture content, which also can lead to rancidity or mould issues. Most foods that have passed the expiration date are already 1-2 years since the actual date of manufacture, add another year or two to that and you could potentially be feeding food that was manufactured 3-4 years ago. There are key nutrients such as Vitamin C that depending on the form of the vitamin used, and the amount added to the food when being manufactured, could very well be pretty much spent before you even open the bag.
As you can see, the worst case scenario of expired koi food is that it has spoiled and could be dangerous and the best case scenario is that it is not as nutritional as fresh food. Either way it isn’t really good, since even if it doesn’t kill them, it is effectively junk food with less health value than before.
In other words once koi food has passed it expiration date it is more or less junk by that point and probably better to feed your fish cardboard and paper.
For best results ALL koi food should be stored in a dark, dry, cool environment and fed within the manufacturers stated expiry date.
Now ask yourself how much if any are you truly saving?