I have this species (Microdontochromis rotundiventralis). I've got them from Germany, 20 fish, and everything was so well, for a very long time - 6 months! They had eggs, fry ... Everything, as in the perfect aquarium!
Then I decided some time ago only to make water change 1 time every 2 week, when I heard that many had had success with it, and in the beginning it went fine too. Some time ago, one of the fish became ill - one of the deformed fish. After some time it died, but I thought that something had been wrong with it from the beginning. Then, the other deformed fish died, and now, one more fish is ill. Now, I only have 14 fish left. The one, who is ill now, has the same symptoms as the other fish had before they died - I am afraid that it’s caused by poor water quality, and will begin to make water change 1 time every week as before. : (
The symptom of the ill fish is as follows: The fish swims in a big group a little bit above the bottom of the aquarium all the time - all together. Suddenly one fish begins to breathe more rapidly and it swims more and more in the back of the group over a period of time. It begins to breathe much faster. There is no sight of sticking dandruff (Is that was it’s called?), mold, or wounds; the fish have normal color, perhaps a bit brighter. At one point, the fish begins to stay in the back of the aquarium, lying on the bottom (with the stomach down, just resting on the bottom). The belly never turns upwards! The fish is now gasping quickly and it stops eating. After some days, the colors are brighter and brighter. And then, the fish dies.
It makes me really, really sad that my fish is dying, because before, everything was so well! I hate to see the fish-group shrink - these fish means a lot to me, and I have no idea what is happening! I'm afraid it is a form of water-intoxication - can that be the reason why my fish are dying? The weird thing is, that this only happens for one fish at a time ...
I hope that there are some who know what this is, and how to cure! : (