Pale Zebra Danios

[chloebo]

I came home in the early morning hours and flipped on lights, looked at my tank, and saw that my danios were pale-looking and hanging out at the surface. I don't see any growths or other signs of illness, no gasping or clamped fins. I immediately checked the watetr and everything was normal - 8.2pH, .25 NH3, 0 NO2, 10 NO3. The only thing i can figurer is the lights shocked them? Everyone seems normal this afternoon.

It's a 55 gal, bubbler going, filter going, water temp about 82F. They are recovering from a bout of ich, so right now the only occupants are 5 danios and 1 platie. (I am filling out the platie's school, they are under quarantine.) Any other ideas?

 

[DeanoL83]

It could be that they were still asleep. I have done that before, came home early, put the lights on and all my fish had no colour. My neons were dull and my rummynose didn't have a red nose.

My only assumption could be that they turn their colours off while sleeping so they are not an easy target for predators. It takes a while for their colours to come back on, normally when they are fully aware and active and feel safe again.

Have their colours come back yet?

 

[Liv15]

Yeah fish' colours go really dim and dull when they sleep so maybe that, also when they are stressed.

 

[Byron]

Fish colours and patterning for most species will "wash out" or fade during darkness.  The same can occur when the fish is under stress, as someone mentioned.  But from the data here, it is more likely the normal diurnal change.  However, turning on fish lights in a dark room will cause sudden shock and this can serious harm fish.  Something similar occurs when the tank lights are suddenly turned off and the room is in darkness (meaning, without ambient room lighting).  This was discussed in a couple other threads recently, and I explained it more in post #4 in this thread:
 
http/www.fishforums.net/index.php?/topic/436145-lighting-in-an-unplanted-aquarium-should-i-structure-it/
 
Byron.

 

[attibones]

Could also be due to stress. 82 is pretty high for zebra danios. Not to mention it shouldn't really be normal to have an ammonia reading in an established tank (and I'm assuming this tank has been cycled). On second thought, you could have lost some bacteria if you used medicine for the ich.

 

[Tongue_Flicker]

Yeah fish' colours go really dim and dull when they sleep so maybe that, also when they are stressed.

Most likely this.