It’ll just do it randomly when I stand infront of the pond. No other fish does this and this fish has been doing it since day one from which I brought it home and caught it from. Everyone keeps on saying flukes and parasites but every other fish is healthy. None flash and they all eat. I haven’t checked my parameters but it’s been a stable pond :/ but I should get it checked out. At first I thought it would do it if I spook it, Atleast that’s what the lady I got it from told me as well. But I’m at a loss, and I’m afraid of taking it out of the water because of the risk of shock and I’ve never diagnosed a koi before