Fish Dying Rapidly, What Could it be?

[Xenotilapia]

About 2 months ago now I got a Number of New Tanganyikans.
C. Foai "Mbita"
X. Flavipinnis "Nyanza Lac"
T. Vittatus
C. Leptosoma "Kitumba"

In the Last 2 weeks I lost all 11 Foai "Mbita" to what I orignally thought was bloat.
Within the last 4 days I lost 3 of the X. Flavipinnis.

The Tank is a 125g Filtered by 2 Aquaclear 500's I do 30gallon water changes every Sunday without fail since I aqcuired them. It is well Aerated, as I have 2 36" Bubble Curtains across the back portion of the tank and a Large Sponge Filter in 1 Corner.
My Nitrite and Nitrate Levels are 0 according to my Testing, and no Detectable Ammonia. A PH of 8.3 and the tank is a steady 79F
I feed them Tetra Tetramin Pro Crisp, Nutrafin Max Spirulina Flake, Nutrafin Max Plus Mysis Flakes Daily, and Frozen Brine Shrimp every 2 days.

I originally suspected bloat when the C. Foai began dying as I know they can be susceptable to bloat from a high protien diet (Brine Shrimp) I ceased feeding BS immediatly after 2 Foai died overnight. The Foai all exhibited the same Symptoms just before they died:
-Initially very Stringy, sometimes almost clear Feces
-Listless on the bottom of the Tank (Beach Sand Bottom)
-Rapid Gasping
-A Pink/Purple Discoloration and a General Faded look
-No Interest in Eating


These are the signs within hours of death. I work an 8 hour day. I left on one Particular morning after removing 2 dead C. Foai several days earlier. All was well with the other 9 Swimming and eating Vigorously as they had every other morning.
I came home to 5 dead in an 8hour timespan with 2 more on the way out (with the above described Symptoms) The 2 died within hours, maybe 3hrs at most from the time I arrived home. At this Point I had not been Feeding the BS for almost 4 days.

The Remaining 2 lasted another 5 days before dying within about an hour of one another.

I do not suspect bullying of any Sort as I spent roughly 2hrs per day Photographing the tank with a new Camera I recently Acquired, and saw nothing out of the ordinary between any of the Tank inhabitants.

As for the X. Flavipinnis, I'm not sure what is taking these little Beauties from me. This wave of Death comes after 47 days of Rapid Growth from all species Acquired.

The X. Flavipinnis exhibit Similar Symptoms as well
- RAPID Gasping (I mean it's nuts)
-Stressed Coloration
-No Interest in Eating
I don't suspect bloat with the X. Flavipinnis, as to my knowledge they eat a fair bit of protien in their Natural Habitat

The only thing I can conclude from this whole fiasco is that they may all be affected by an infection, or maybe even Flukes or Parasites...

I just don't have a clue, and I am at a loss as to what to do!

Russ

[Courtney]

Did you add in any new fish and how long have you had you newest fish? Do they have any white spots on them? Are they flashing? (rubbing on rocks) Are you sure there is no aggression by a bully?

[Dan Woodland]

Russ,

You seem to have a good grasp of fish keeping from your detailed description, have you thought about a contaminant in the water, substrate or decorations?

Some questions that come to mind?
What is your substrate?
Is the tank new or recently repaired? Have you kept fish before in this tank? etc
Did you add any new fish in the last couple weeks? (do you quarantine new arrivals?)
Do you live where your water source may have been treated differently?