What cause fish to scratch against rocks?

[xa]

AT. (Scratch against rocks or tank glass)
Signof Ick? or some other problem.

 

[armageddon]

My trigger started scratching against the my rocks every night around the same time. Shortly after he developed ich.

 

[sebae0]

usually the sign of a parasite, aka ick.

 

[beth]

Yes, external parasite....commonly it is ich, but not necessarily.