Lost my gold Ram three days ago leaving me with a brilliant blue and German blue Ram, 2 dwarf gouramis, and 8 Danios in my 20 long. I think I'm stable now with the nitrates at 30 1 day after 40% water change and gravel cleaning.
Agree with posters who helped me go through the paces for a healthy tank and feel the following could be problem sources:
didn't go deep enough in the gravel when vacuuming, let my filter get dirty, forgot to clean the foam filter I have attached to the intake tube on my Acqua Clear 30 (took me 10 minutes of squeezing in clear water to clean it). Those things stressed the tank and the 3 Rams who died were too young to handle that environmental stress.
Hope my problem helps others who notice fish stress and thanks to all for your input .