wierd colour patterns in my tetras

[TETRASIAN]

every few night at about 3 or 4 am when i happen to be awake... i grope around the dark to my tank with a torch light just to spy on the fishj... i notice that the tetra(neons cardinals and glowlights) just float around like their dead.. some hanging on to the plants... yah i guess they are sleeping but then all thier blue colouring is gone... just a pale red... even the glowlights lack luster..

this is normal right?

 

[Lateral Line]

The red colouration is a genuine pigment, as long as there is a little light, you will be able to see the red colour.

The blue/green line is not a pigment. The cells that produce the highlights, (called iridophores incidently), contain guanine crystals. These refract and reflect light so there needs to be considerable light falling on the cell from the right angles for these markings to show.

I'm guessing your night time forays to the tank are in low light.