Tetra's Pale When Sleeping?

[kmaisch]

Hi all,

I'm relatively new to aquariums, so sorry for this newbie question!

Is it normal for Neon Tetra's to become pale (loose their blue stripe, etc) when the lights are out or when they are sleeping. For example, when I come home after work and it is fairly dark - I turn on the tank light and find all the tetras at the bottom of the tank (resting) and all very pale. It takes a few minutes after the light has been on for them to get their colour back.

I assume this is normal, but thought I'd check anyway

Thanks,
Kim

 

[Luke_e]

Yup, this happens to most of my small fish. They'll colour up once the lights are on for a bit in the morning .

 

[IovaykInD]

Yep, Luke_e is right. When the lights are turned off, they lose their coloring. In the wild, I think I read it's because during the day, they use the stripe for identification, but since there's no light at night, they have no need for it.

Isaac

 

[kmaisch]

cool, thanks for the quick replies!

Kim

 

[IMCL85]

You should see my cardinal the other day at morning his like completely white.

 

[Lateral Line]

I explained this behaviour in this thread.

Additionally, the blue line on Neons is not a pigment. It is produced by cells called iridophores which contain layered guanine crystals. These reflect and refract light to acheive their result. If there is no light falling on them, there is no light to reflect or refract.

 

[kmaisch]

thanks for that

 

[SnowyzMom]

In that case, can anyone explain why in my group of Neon Tetras one doesn't have a blue line but a golden green line down his side? Or is s/he just trying to make a fashion statement? All fish are otherwise identical and in very good health, had them for over 18 months. This one just isn't....blue. Everything else about him/her is identical to the others. I guess there always has to be somebody who draws attention to themselves eh?

 

[Griz]

On the same subject, I've noticed something interesting with my One-lined pencilfish Nannostomus unifasciatus. They lose their colour like other fish but also change their pattern. They become blotchy, like a military cammoflage pattern. The difference is quite striking. I assume that this is exactly what the purpose is; to help them hide from predators while sleeping. This is the only fish I have ever noticed doing this but I assume that others must do this too.

 

[Lateral Line]

>>> doesn't have a blue line but a golden green line down his side?

There are a couple of things which spring to mind. Firstly, as I said above, the iridophores produce colour by reflecting and refracting light with crystals. If the crystals were thicker/thinner/otherwise different from normal, the line would take on a different colour. Such minor abnormalities are quite common. Indeed, a number of "special" neon types are available where these faults have been selected for, things like Diamond Head Neons for example.

Another possibility is that the fish has a degree of xanthism. Again, xanthism is a genetic trait which in some species has been selected for. Xanthism creates a golden hue on a fish, how much varies. A xanthic golden cast would tend to "green" a blue iridophore.

 

[SnowyzMom]

>>> doesn't have a blue line but a golden green line down his side?

There are a couple of things which spring to mind. Firstly, as I said above, the iridophores produce colour by reflecting and refracting light with crystals. If the crystals were thicker/thinner/otherwise different from normal, the line would take on a different colour. Such minor abnormalities are quite common. Indeed, a number of "special" neon types are available where these faults have been selected for, things like Diamond Head Neons for example.

Another possibility is that the fish has a degree of xanthism. Again, xanthism is a genetic trait which in some species has been selected for. Xanthism creates a golden hue on a fish, how much varies. A xanthic golden cast would tend to "green" a blue iridophore.

Thank you very much! I think this really answers my question.