Golden pencilfish/Nannostomus beckfordi coloration

[illumnae]

i have a bunch of pencilfish that i think are golden pencilfish acting as dithers in my apisto tank. they look exactly the the online pictures i find on aquarium pictures (gold line above black line, light brown body, red fins/tail with some light blue on the ventral (?) fins)...however, i notice that when i turn off the aquarium lights, the black line seems to fade away and are replaced by 2 longish black spots on the body...is this normal?

[valice]

It is their form of camouflage in the wild.
If you stay around the tank long enough, you will notice that they will stay to sleep near to the water surface.

Do they look abit like this?

[illumnae]

it looks something like that, but the black spot doesn't go all the way around the back i think, it's just 2 spots below the gold line...mine also don't have 2 gold lines like this one, only 1 gold line where the top one is in this pic, and the black line below it =)

but yep when the lights go off the 2 spots appear when the black line disappears and they all hang near the water surface

[benny]

Most pencil fishes exhibit the same type of night time coloration that you mentioned.

If you examine their natural habitat, you will find that they hang around the water surfaces, very near the river banks. With the tall long reeds, this night time coloration will allow them to blend in to the shadows of these long tall plants and keep them safe from predators.

As such, there's nothing to worry about. Their normal coloration usually returns after 5 minutes after your lights are turned on.

Cheers,

[illumnae]

yup benny their colouration usually returns by the time i wake up at about 8am and the sun is out =)

thanks for your advice benny and valice! glad to hear my pencilfish are normal keke...i was sold these pencilfish as one-lined pencilfish, only lately then it was pointed out to me in another thread that they are more likely to be golden pencilfish instead keke, gotta tell polyart they label wrongly

[hwchoy]

pencilfish and some tetras have such so-called night coloration.