PlanetCatfish.com

There are two kinds of bad fishfood. One is expired food, and the other is low quality food.

I may have both of them.
My can of pellets, while not past the expiration date, seems to have changed its smell. The new smell is not unpleasant.

Anyone have tips for:
Getting rid of low quality food

Detecting if food has gone bad
but isn't obviously bad

Detecting if food past the date is still edible if it still seems fine

food past the date can be expired in two ways:

1 the vitamins, which will eventually react with air, have detoriated
2 the proteins are no longer good

food in category 1 can still be used, if mixed with good quality new food.