Pet Forum / Aquaria / Cichlids / October 2005

I have an established cichlid tank (6 yrs) with 4 Convicts about 8-10
years old, to which I added 4 young African cichlids (2 Red Zebras, 2
Blue).  The next day I saw one of the blue ones suddenly flip out and
start darting around the tank completely out of control, then it calmed
down. The next morning it was dead. I then watched the other fish for
most of the day and they seemed fine, then in the evening one of the
other blue ones who had been normal up to that point suddenly went
berzerk, zooming, spinning, bashing into everything in the tank, then
it calmed down. Then in a snap it repeated the frantic darting until it
knocked itself out. Then it recovered, then did it again and again
until it killed itself. This took 20-30 minutes. I've never seen this
before. I checked the water chemistry, temperature, filter, everything
was fine plus I know the other fish hadn't been harassing them. The
fish had no signs of visible disease, no discoloration, they looked
perfectly healthy. So I don't know why this happened. Does anyone know
what it can be, or have any advice? Thank you.