In the last week or so, I have noticed my fish are not eating frozen mysis shrimp. They pick at it a bit, and often spit it out. They eat live black worms very aggressively. They feed normally on flake. The mysis shrimp batch expires in 2018. This is not a new purchased batch. I've been feeding them with it for months. It is hikari brand cubes. I used with and without garlic.