Narcoleptic Koi?

[cguarino30]

So I have a group of about 30 koi fry (about an inch long) in a 75 gallon tank, that I am growing out to put in an outdoor pond. I'm noticing an interesting behavior. occasionally, one of them will sort of "nod off." The essentially stop moving, swimming, everything, and will just drift with the current, sometimes even to the point of letting themselves be flipped upside-down, and just when I start to think they've died, they snap back to consciousness, right themselves, and continue swimming as if nothing has happened. I see no signs of sickness, and they're growing well, so I'm wondering if this is normal or if there is some sort of problem. Any help is greatly appreciated. Thanks.

 

[A. Nonymous]

Is this one particular koi each time?

 

[cguarino30]

not really. There are a few that do it. Some of them just do it for a second or so, and some will literally lay on the surface as if they were dead for as long as a minute, even letting the others come up and pick at them a little before they snap out of it and continue swimming normally. Also, this has been going on for over a week and I'm not suffering any major losses, or noticing any other sumptoms. I've never seen anything like this before. My only idea is that maybe there is too much current in the aquarium. They don't seem to have any trouble navigating through it, but maybe they need to rest or something and they're not getting the opportunity. Do koi fry sleep?

 

[NeonFlux]

Interesting behavior...