Fish Dying in Good water conditions
I have a 55 gallon tank. The past year I have had 5 tiger barbs and a pleco. Recently I added 5 more tiger barbs, 2 pictus catfish, and a clown pleco. I also added live plants at the same time. The first week all the fish were doing GREAT. The second week started with both catfish dying, then my older tiger barbs, and each day one or two more have died. Now I only have my old pleco and a few tiger barbs. The temperature is perfect, water has been tested multiple time and tested good. I have no idea what is going on.