Thanks everbody for your advice and oppinions. It is a little embarrasing: I told you that I had two borellis and two unspecified specimen, well, the borellis aren't borellis. The thing is that in trying to determine the species I referred to a SA dwarf cichlid book that does not include Nanacara Anomala, and so since the fish fit best to the description of A. borelli, I assumed... Anyway, I am now almost positive that I have two N. anomala, and one specimen of N. taenia. One more undetermined. As to the water values: I cannot give you nitrate, nitrite or ammoniak measurements, since I don't have the kits to find out. The four remaining fish are doing well and show no signs of sickness, but then - until their sudden death the Rams look perfectly fine. One more fact that might help is that during the last week I had lowered the pH and hardness, because my water was really hard (16 dH) and had a pH of 8. I lowerded the pH first by adding rain water with good pH and dH values, then I added water treatment from the pet store, and finally I got an RO unit and did partial waterchanges. When it happened the dH had gone down to 13 and the pH was at 7.5 So I am wondering if it could have been denitrification setting in and killing the fish by O.D.-ing ammoniak. But just a wild guess from a non-expert. For those who want to know the tank setup, its 25g and has dense plants, two or three rocks and coconut halves for hiding place. Martin - -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*- Martin Rausch Dept. Communication & Cooperation Fraunhofer Institute for Computer Graphics - -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*- ph: +49 (6151) 155-211 fx: +49 (6151) 155-559 ml: rausch@igd.fhg.de wb: http://www.igd.fhg.de/~rausch