Why do Pacus change color?

[Juxtaroberto]

During the day they're a dark gray...

But whenever it's been dark for a while and I need to turn the light on, I turn the light on and my Pacu is a dark pale gray color. I thought it was the light... since during the day its in natural sunlight, except 4 minutes later I look up and she's dark gray again.

Does anyone know why this happens?

 

[Juxtaroberto]

Anyone?

 

[Juxtaroberto]

Hellooooooooooooooooo

 

[pacu mom]

All my fish turn pale when they are resting or sleeping in the dark.

Here are my fish when I turned on the light to take their picture. They are also not as rambunctious when they are sleepy. The oscar can have a pale gray color instead of black. When they're fully awake, their darker coloration comes back.

 

[Red Devil]

i had pacus for over 8 years and mine never changed different shades of gray color enough to notice it much.. but they did lose their red belly color as they get older and bigger... it faded to pinkish..

 

[Red Devil]

How old are those guys now... Pacu MOM.?

 

[Juxtaroberto]

All my fish turn pale when they are resting or sleeping in the dark.

Here are my fish when I turned on the light to take their picture. They are also not as rambunctious when they are sleepy. The oscar can have a pale gray color instead of black. When they're fully awake, their darker coloration comes back.

See, you know what I'm talking about. But does anyone know WHY?

My Pacu becomes so pale you can see she still has red coloration on her, but during the day she's so dark you can barely tell.

 

[pacu mom]

I don't know how old they are, as they are rescued fish. They've been in the tank for 3 years now. They were rescued in the summer of 2005. I'm sure the fish were all stunted from the high nitrate levels they were exposed to. The pacu were about 15" when we got them (in their 55 gallon-12" wide tank). They have grown very stout. They are now at least 10" tall and 4" wide...bigger than in that picture which was taken several years ago. I had just figured out how to use my new camera, so woke up the fish to try the camera out.

 

[pacu mom]

See, you know what I'm talking about. But does anyone know WHY?

My Pacu becomes so pale you can see she still has red coloration on her, but during the day she's so dark you can barely tell.

I don't know why, but I do know that all my fish do that--my oscars and the bettas that I used to keep.

 

[Zoodiver]

Protection and the biology of the animal.
When in a state of 'less awareness' or 'rest', they lighten to blend. A lot of fish will also pale with sickness or distress (like a predator, or when being shipped).

When fish rest, the blood is circulated less to the outter regions of the body, instead focusing on the internal organs and systems needed to keep them alive. Shutting down like that allows them to rest without being fully asleep like mammals do. Less circulation is reflected in the loss of color. In pacu, you see them pale. In brightly colored fish like cichlids or saltwater reef fish, their amazing reds, blues and yellows fade to much lighter tones.