I am having a problem with my 72 gallon tank. I am losing about 1-2 fish a day for the last 3 days. I have been monitoring the water it is rock steady. ph 7.2. ammonia 0. nitrates 0. nitrites 0. I have city water. Chlorine is 0. Temp is 78-79. I run an AquaClear 500 filter. I changed the carbon filter and sponge filter about 2 weeks ago. I currently have the following fish in the tank: 5 platies, 8 zebra danios, 4 longfin leopard danios, 4 lemon tetras, 4 flame tetras, 2 emerald catfish, 2 corydoras julii, 1 small angel fish (new), 9 gourami & 2 plecos. I typically feed a small amount in the morning and a small amount in the afternoon. My LFS guy could not find anything wrong with my water sample, this confirmed what I had already tested. The only thing that he came up with is the possiblity that I may have done to drastic of a water change a couple weeks ago. I changed between 30-40% of the water because I had been overdue to change the carbon filter by about 2 -3 weeks (they were out of stock at my LFS). I have not noticed any fish not eating. I have lost in the last 3 days: 1 flame tetra, 1 lemon tetra, 1 blue crosby gourami, 1 angel fish (new), 1 khuli loach. Last week I lost 2 corydoras julii. I also have life plants in the tank and many small snails. I am at a loss. Help please.
