Clowns gasping at surface when lights go off

[Formulator]

Very strange behavior just started with my two ocellaris clowns in my 125 reef tank after being out of town for two days. While I was gone, I left a single T8 actinic on along the back of the tank. I usually use this as a nightlight when my main bulbs go off, so I can still observe when I'm up past tank lights-out time and I turn it off when I go to bed.

The first night after being back in town I turned the light off and both clowns immediately went up to the top of the water gasping and lying sideways along the length of where that bulb sits above. It was like they were trying to get to the missing light. I went to bed a little worried and 4 hours later woke up for the bathroom and checked while I was up. They were still floating around up there. In the morning, 7 hours after turning off they were still there, but as soon as I turned the light back on they started swimming normally and went back to the powerhead they are currently hosting :facepalm:. It was almost immediate.

What gives? I'm worried they are going to fall over the weir into the overflow the way they float when I turn off the light. Anyone else seen this behavior or have an explanation? Water params are all nearly perfect. Only thing would be very slightly elevated phosphate (0.06 ppm).

Thanks!

-Chris

 

[Formulator]

Anybody?

 

[D-Nak]

Since they're normal during the day, I wouldn't worry about it. Maybe they're just choosing to sleep at the surface.

My first thought was that there is a pH shift, but that shouldn't affect the clowns much and it wouldn't happen immediately.

I literally have hundreds of clowns right now (lots of babies in grow out) and a couple of my pairs separate at night and one clown in particular sleeps at the top of the tank. I wouldn't consider it normal behavior, but I don't know what normal behavior is for clowns -- they're just weird.

 

[OrionN]

Do you have a skimmer? Possible low in O2 when the light go out if you don't have skimmer running.

 

[Formulator]

Yep, great skimmer and a fuge on opposite photoperiod.

 

[Sk8r]

Clowns, especially young ones with no fixed home, are apt to sleep in weird places. You're right being concerned; I would be looking at it askance, too, but it could be ok.

One thing a tank needs day and night is real strong flow. My benchmark is 950 gph per 50 gallons, with a strong skimmer as well.

 

[Dkuhlmann]

Yep, great skimmer and a fuge on opposite photoperiod.

I would try running your skimmer 24/7. There is no need to turn it off.

From your description it does sound like low oxygen, but doubtful since it only happens when you turn off the lights. Are any other fish doing the same? If not I'd just let it fall under clowns are weird fish. :lol:

 

[ThRoewer]

Give them a home. A ceramic flowerpot of appropriate size will be a perfect anemone surrogate and I have yet to find a clownfish that doesn't accept it.

Sent from my XT1254 using Tapatalk

 

[Zalick]

One of my clowns used to sleep floating on the surface. I wouldn't be too concerned.

Have you tried turning the lights back on when they are on the surface? My guess is they will swim around like normal.

I think this is just where they want to sleep.

 

[Fiver]

Both of my clowns also occasionally sleep at the very top of the tank tilted to the side. I once checked on the tank and thought they were gone before realizing how they slept. The black trim on the tank obscured them from view.