A couple behavioral questions

[Troy McClure]

I'm trying to figure out whether or not my discus have something internal...like head worms, protozoa, etc. Sometimes I see them hanging around the tank with their heads down - I'd guess it's at a 45* angle, maybe less. I don't always see this behavior though and not all of them do it. I saw it yesterday after I fed them and one of the them was chased off. He hung out almost on the the opposite side of the tank with his head down. When they get really spooked and huddle together (if I accidentally close a drawer too hard) some of them will be huddled up with their heads down. They still swim around seemingly OK, they eat like friggin pigs, and the water is changed 50% per day. Sometimes when they spook they sprint to the other side of the tank, but they'll do it swimming sideways. It seems to me like this is just defensive behavior because I can't see any other signs of illness. I'm just curious here. If they need to be treated for something, I'll do it, but I'd like to know if this behavior is not-unusual for discus.

If I see anymore of this behavior tonight, I'll try to get pics.

-edit- I should add - Eyes are nice and clear and I haven't noticed any discolored feces.