Clown paralyzed by light.

[Teelie]

Hi there, I'm relatively new to a reef tank but, observed something rather odd today with my clown fish.

I got home a little later than normal (just before dark), and went to feed my fish - an ocellaris clown, a pj cardinal, cleaner shrimp and an assortment of snails and crabs - when I flicked on the light (second to lowest full spectrum setting) my clown fish was suddenly paralyzed and his eyes looked really strange. He sat on the outflow tube barely able to move and , it seemed his tail was stuck mid stroke. I immediately switched to the lowest blue and, in seconds he was right back to normal and continued to greet me as I fed him and eat as normal.

Is this a normal thing ?

 

[Jay Hemdal Verified Community Expert]

Hi there, I'm relatively new to a reef tank but, observed something rather odd today with my clown fish.

I got home a little later than normal (just before dark), and went to feed my fish - an ocellaris clown, a pj cardinal, cleaner shrimp and an assortment of snails and crabs - when I flicked on the light (second to lowest full spectrum setting) my clown fish was suddenly paralyzed and his eyes looked really strange. He sat on the outflow tube barely able to move and , it seemed his tail was stuck mid stroke. I immediately switched to the lowest blue and, in seconds he was right back to normal and continued to greet me as I fed him and eat as normal.

Is this a normal thing ?

Light shock is a thing, it can even be fatal if the fish has some other predisposing issue (like fatty liver). I always ramp up the lights slowly - turning on the room lights first, then ramping up the tank lights over a few minutes.

We had an issue at a new public aquarium I managed. We were having weird fish losses and fish jumping out of the tanks at night. Turns out that the new security staff were using strong flashlights as they did their walkthroughs. I had them stop that, and then just arranged for *some* of the building lights to stay on all night - like very fourth one, to allow the security folks to see where they were walking without using flashlights.

 

[Mr. Mojo Rising]

Fish do better on a set schedule. If you randomly turn the lights on and off it will startle the fish every time.

And if its dark and fish are sleeping, I will not turn the lights on to feed them, they will need to wait till the next day.

 

[GARRIGA]

I do the same thing… freeze when woken from a deep sleep from light or loud sound