Something has changed, obviously. If it's not anything that you've done, then it's either something in the tank that has changed, either by nature or by human accident (and thus you wouldn't have noticed), or with the fish itself.
What are the water parameters? (
ammonia, nitrates, nitrites)
What do you normally feed your fish? If you had trained it to eat pre-dead food, it could be that your fish is, for some reason, reverting to its preference for live food. I don't know how to get over that, but it might help you feed the fish until you get this figured out.
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