Why does my black neon tetra lose its black stripe over night and regain it after the light's turned on?

Question

I have two black neons, but it only happens to one. It's also less active than the other, but it eats and seems healthy otherwise. My tank is a 10-gallon with 10 small fish.

Answer 1

Most smaller fish lose color at night. It's a defensive thing that makes them harder for night time hunters to see them while they rest. It's more pronounced in some fish than others and some recover their color faster than others.

MM

Answer 2

Some of my regular neons have lost color over night too. All I could think of is that their pigment is more sensitive to light than the others' were. It may be something in those individual fish where they needed the light to produce the pigment. All of the fish were healthy otherwise.

Answer 3

Its because they lost their color naturally at night, and regain it when the light is turned on. If you were a colorful tetra in the wild, you wouldn't want your color to shine when it's nighttime, would you?

~ZTM