I had 6 Melanotaenia praecox in a 20 gal
(set up a month ago) with 5 small Calvus, 3 small Haplocromis Insignis, 3 small Aulonocara flavescens and a Golden Nugget Pleco. Everybody seemed to be getting along nicely. I have been doing water tests every 3-4 days since I set it up and have been doing 20% water changes every 2 weeks. I am running a Aquaclear 500 (I know its overkill). I have never had any positive tests for Ammonia or Nitrite. My ph
is at 7.6 and water temp at 81-82 degrees. Everyone seemed to be eating well and mobile. Suddenly yesterday I lost two of my Neon Rainbows and today I lost another one. Any ideas as to what is happening?