Who Gives A Fish Forums

I've noticed that my LPS corals change throughout the day, they can look nice and plump one minute and then be deflated the next. It's like they're going through some sort of daily cycle. I've seen anemones do the same thing, and to be honest I'm not entirely sure why it happens. As long as they're ...

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It's also possible that nudibranchs are the culprits here. They're nocturnal, so they'd be active at night, which could explain why you're not seeing them. They do tend to take random bites out of corals, which might fit with what you're observing.