Gastromyzon colour

[janma]

I came home today and when I looked in the tank I noticed of my Gastromyzon's gone all light except the head. Then it chased away a Sewellia from a nearby rock and the color started to get normal. Never seen this happen before and so my question to all you hillstream experts out there: Is this normal? Theres two minutes between the time when these pictures were taken.

Color Off

Color On

[Mad Duff]

Mine do go lighter on light colored rocks and darker on dark rocks but I have never seen anything like that among mine

That first photo is very weird

[mikev]

I've seen the reverse a few times (on G.Cteno...): white face, restored to normal after a move. Not this.

[Emma Turner]

I've only ever seen colour changes in Gastros either when the fish move from a light to a dark substrate (when the whole body changes colour) or when fighting, as in Mad Duff's recent video: http://forums.loaches.com/viewtopic.php?t=9388 where there tends to be a dark area along the dorsal surface.

Excellent photos, Janne. An amazing transformation.

Emma

[Jim Powers]

I've seen them lighten up while resting on lighter colored rocks or on plant leaves and also when fighting, but I have never seen the head stay dark like that.
Looking at the pic, it seems as if the part of the rock near the fishes head is darker than the rest. I wonder if that could have anything to do with it?