Fish are flashing

I have a problem that I have never encountered in all my years of keeping fish...
First the specs
125 gallon tank been set up for 5 years with 2 xp3's, a Koralia 4 powerhead. Maxima Air Pump with 2 -6" air stones.
Temp-constant 80
Ammonia-0
Nitrite-0
Nitrate-5
PH-6.8

Stock
9" Silver Aro
2-7" Bala Sharks
2- 2.5" silver dollars
7" Geo Altifrons
7" BGK
6" Ornate Bichir
3-2" common Plecos

Sand substrate with a Manzanita wood stump and river rocks for decor.A few plastic and silk plants.

25% water changes weekly. Dechlorinate the water in 5 gallon buckets before adding to tank.

Food
1 feeding a day of a mixture of the following foods (not overfeeding)
Veggie Flakes
Hikari Food Sticks (hand fed to the Aro)
Alge Wafers (Silver Dollars, Plecos and Bichir eat these)
Massivore delight (hand fed to Aro and Bichir, Silver dollar occasionaly steals one)
Shrimp Pellets (as a treat maybe once every cpl weeks)
Blood worms (same as above...as a treat)
New life Spectrum Med. Fish Formula sinking Pellets (everyone eats these)
Nutrafin Basix Floating Cichlid Pellets (again....anyone that comes to the top will eat these)
Omega One Freeze dried Shrimp (Fed as a small treat once every cpl weeks. These are soaked in water for a time before feeding)


Last fish added was the bichir about a month ago.

The story

I got rid of all my Africans a few months back and got these fish as I wanted to get something different. They were all added over a one month period. During that first month I noticed that the Bala Sharks and SD's were flashing alot. I looked closely at them for signs of ich or anything for that matter, but saw nothing. Went online to find out that it could be flukes or it could be early stages of Ich.
Treated the tank with high heat (87) and salt for 2 weeks...fish are still flashing (now all of them), with no visible signs of anything on them...no ich, velvet....I cant see anything. So I treat the tank with Coppersafe for 1 month as per directions...
Finally everyone is acting normal....for about a week.
I notice with my Aro mostly, that he is yawning alot, and doing the head shake, like something is irritating his gills....last night he was swimming up and down the glass for about an hour..then he seemed fine. Bichir flashed a cpl times and one of the Silver Dollars was flashing a few times as well.
Today I come home from work and see one of my Bala Sharks Flashing 4 or 5 times in a row and shaking his head alot...really irritated with something. Aro is coming all the way to the bottom of the tank and doing what looks like trying to pick something up from the bottom of the tank with the side of his mouth....then he does the same motion against a rock. He also is "snapping" his mouth at nothing and then makes a chewing motion with it.
Bala sharks are going up and down the glass....
Not breathing rapidly and the plecos have not been flashing.


Then it all stops and everyone acts completely normal. This is an off and on thing that I have been dealing with for the past cpl months. There are no visible signs of parasites or fungus or fin rot, etc....just this behavior that is telling me that something is wrong. All my water parameters are consistant with what I originally posted at the top....looking at the tank right now, and everyone looks healthy and happy...good color...good appetites...but something is not right.
How do I treat for something I cant diagnose? I do not want to just throw meds at the tank haphazardly...hoping that I figure it out.

So I turn to you guys for any input.

I have exhausted my avenues with the internet...now I am stumped!!!

Any ideas???


Anyone???

Thanks Lupin

I will give it a try.

2.5 days with Prazipro in the tank and NO improvement. 25% water change before adding it

my 7" Geo Altifrons died today. Last night started breathing heavily...gills were a little red...air was on full blast...dead when I got home from work...Bloody hell!!!!!
Aro is very irritated...up and down the glass......I fear he is next

I cant see anything visible on the fish.Checked the water parameters last night and every thing is the same.....

all my years of keeping fish and I have never had something taunt me like this..

I am almost ready to pack it in.

If the Silver Aro dies.....I quit!!!


ANY SUGGESTIONS WOULD BE APPRECIATED AT THIS POINT.

If after the 5 days of Prazipro treatment and they are still all like this....then what??? wait the 3-5 days and treat the tank again???

My Aro has stopped eating now...I had 2 flish flash once...maybe twice last night, so overall I thing everyone seems to be doing better....but the Aro is doing worse. He is swimming INTO the current of my powerhead, which I positioned to keep away from him. He is swimming with his nose up against the glass, side to side and up and down...skittish of all other fishes (REALLY UNUSUAL) still yawning alot and doing quick snapping of the jaw motions. Obviously something is bothering his gills. Last week he was picking up sand and pumping it through his gills. There are no visible signs of anything. Not breathing rapidly...no red gills or swollen gills...I fear he is going to end up dead just like the Geo....my two prize fish!

PLEASE HELP

Here is a link to a vid I took of him

http://s195.photobucket.com/albums/z248/magnum-016/?action=view&current=Arovid.flv

TTT

Nobody has ANYTHING?????

I looked as closely as I could at the dead Geo and could see nothing

I have since taken a sample of my water to my LFS and it tested out the same as my tests.
I just finished doing a 50% water change, replenished the Prazipro, am bringing the temp up to 83, turned off the powerhead the Aro was obsessing with, Air pump on full, added salt, and turned out the lights.....anybody got any other ideas....because at this point I am just "wingin it"