Sick discus?

Hello, i'm new here and from the netherlands so i hope my english is not to
bad.


Mij discus (1 of 5) is doing something crazy.

He (or she) swims arround in circles in a very fast and then i mean a very
fast speed. He's hitting the glas and did even hit the 'roof' of the aqarium
and thats about 10 cm's above the surface.

after this he lays down for a short moment underneath a wood. Within the
minute he's swimming again and you will se nothing strange about him/her.

any idees. I know some of the discus holders here have had the same problems
but no one seems to know whats the exact problem (worms mabey)

the no2/no3 are both zero to nothing and the Ph is 6.1 / 6.4 and the Kh is
about 6.

please mail me.

thanx
Leon