Stress to cause scratch?

[guille2007]

Can fish to scratch against objects if get frighten?

I have notice my fish to do that after turning off the light at night, don't know if it is stress related or so since they don't do it during the day while light is turned on, they have been doing this for a long, at the begining I though that it was something related with WC, but have seen this even during days with no WC. They show a normal behaviour, good appetite, no white feaces.

[Merrilyn]

If everything else is normal, I wouldn't worry too much about it.

As you turn their lights out, you may appear like a large shadow on the tank, and for them large shadows usually mean predators, so they make a dash for cover.

You might like to try leaving the room lights on till after you turn the tank lights out, or perhaps even lean over the tank from the side to turn the lights out, rather than stand in front of it..

[guille2007]

Ok, thanks for advise Merrilyn