Fish Look Ill And Pale At Night?

[dorecs]

Hi,
My tanks been going a while now, i've got 6 neon tetra and 4 Norman's Lampeye killi fish, in a 7 gallon tank with two medium sized plants.
Before I go to bed at night, I check on the fish and the neon tetra's have lost all their color, nearly completely pale white, and the lampeye's eyes stop shining and they go right to the top of the tank and are very twitchy.
 
I was worried all night but in the morning they were all fine, the tetra's had their colors back and swimming round happily.
I don't think this is a normal pattern for fish, Is there a cause and is there much I can do?
I got a water test a few days ago and was told ammonia is 0 and there's a 'whiff' of nitrite.
Thanks for the help,

 

[KrazyKuhli]

They are settling for the night, Fish loose their colour when they rest (less colour, less the predators will see them) kinda like going to sleep for them.

 

[eaglesaquarium]

yup...  Its normal.  Nothing to worry about.

 

[fluttermoth]

Some fish can change colour quite dramatically, or behave very oddly when lights are out, or go on or off.

Tiger barbs sleep nose down in plants and if you switch the light on, from total darkness, they do a weird spiral downwards, like a leaf caught in an eddy. Terrified me the first time I saw it; I thought they were going to die!

My false neons lose their blue altogether at night and go a rather nice copper red colour, and if the room is dim, but not dark, when I put the light on, they're a gorgeous deep purpley blue; they go paler and more green after 10 or 15 minutes. Sometimes you get one that's been sleeping behind a leaf, and they'll be half red, half blue; or red on one side, blue on the other.

My dwarf emerald danios are really shy and normally stay low down in the tank, in the plants but one night I put my iPod on top of their cover glass with the backlight on, and they all swam up to the top and were jumping up and swarming round it.

 

[bluesword23516]

Yep, my neons loose color too, and my guppies loose all color except for their black which actually makes their tails blend in so they kind of look like little fat sticks.

 

[Freedom]

Wow, interesting thread, I had no idea about this!

 

[eaglesaquarium]

My dwarf emerald danios are really shy and normally stay low down in the tank, in the plants but one night I put my iPod on top of their cover glass with the backlight on, and they all swam up to the top and were jumping up and swarming round it.

 
 
I wonder if they normally eat fireflies or something similar in the wild?   
 
That would be pretty cool to see... I'd probably do it so much that they would stop!

 

[fluttermoth]

It was tempting to do it again, but their tank doesn't have a great lid on it (there are gaps all round the cover glass) and I was worried one was going to jump out! 
 
The fireflies is a great thought; I wondered whether they normally spawn at a full moon.