[Amp2020]

If breeding, I would not use expired food. Especially if it had been open for a year.

For the average fish that I'm not too concerned about color and size. I wouldn't have a problem feeding a sealed expired food. Once the container is opened. You risk dust mites and tiny insects, like beetles, contaminating the food.

For bottom feeders or feeding local pond fish like bluegills, I'm sure they'll be happy with anything they can get. If the food smells funny don't touch it, or continue to breath the dust. I've seen food go bad and wouldn't be hard to imagine it making a person sick from mold or fungus spores.