Do fish/loaches lose color when they sleep?

[stephane.savard]

I've had two loaches in my aquarium for about four weeks now, and this morning I saw something happen to them for the first time.

It was 6 am, and the lights (on a timer) turned on, revealing all the fish. However, one of my loaches (Schistura mahnerti), had lost ALL its color. It looked albino! The other was still hiding/sleeping under the large river rocks, so I have no idea if both loaches lost color during the night.

Usually they are dark gray/light gray stripped (the picture is of the actual loach in 'daylight' colors), but now the stripes were barely visible on the tail and the whole fish was whitish-yellow with a hint of striping.

Within half an hour the loach had regained nearly all its normal coloring. I didn't think to take a picture, but I'll see if I can manage it tomorrow morning.

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[Lady Hobbs]

Several fish do that. My neons are almost transparent when I wake them up.

[Deleted User]

It could have been the shock of bright light that caused this reaction. It is better to turn on a room light first for 15 mins or so before the tank lights go on. Less of a shock to them if the room is dark. :ssmile:

[fins_n_fur]

Many fish do, indeed, lose their colouring when "sleeping". It comes back to normal once they "wake" up. It can be incredibly frightening the first time that you see it.

[jb300m01]

Yeah, it's normal for fish to change color depending on a lot of things. The only fishes that I have not seen change color in my tank are the cories & hatchets. The loaches, barbs, & the color changing sailfin pleco will change as you look at them.

Put it this way, do you look your best first thing in the morning? :hmm3grin2orange: I know I do not.

[Brookfish]

Yes it's quite common for fish to change colour,
very nice pic btw, beautiful loach!!