african cichlid diseases

Question
I have a 95 gallon fish tank with african cichlids and I have lost at least 5 within the past month or so. My latest sick fish is now floating vertically in the tank and I am trying to determine what is wrong with him in order to treat the tank. I have lots of new babies ,all different sizes so I would like to to protect all of them as well. The tank has been set up for 15 years and it is cleaned and the water is changed by 25-30% every 2 weeks. I have 2 filtration systems that hang on the back that have biological, chemical and mechanical cleaning systems working. I keep my ph  very high and my ammonia and nitrate levels are within normal limits I just do not want to lose any more of my beautiful, adult  fish. Any suggestions?

Answer
Hi Abbe;

I am really not an african cichlid expert but I can suggest a few possiblities.

Could the tank be overcrowded since the fish have reproduced?
Could there be a fish or two that seem to be exceptionally aggressive and bullying the victims?
What are the general symptoms of the fish before they die?
Do they appear to be torn up, bloated, swollen, thin or pinched bellies, etc?
What is the actual level of ammonia, nitrite, nitrate?

Let me know if any of these things seem plausible or if you think of anything else and maybe we can figure this out...

At Your Service;
Chris Robbins