Hi, I hope someone can help me. I have a 90 gallon tank and it has been up and running for about 1 1/2 months now. I had a little spurt of my ammonia and nitrate and nitrites going up and now everything has returned to 0 .. It has been at 0 for about a week now and I have recently added 10 new fish into my tank. For the past couple days I have lost 6 fish and my testing kits are still at 0 for all the stages (ammonia, nitrate, nitrites) . I am wondering why my fish are dying. The kinds of fish I have are; barbs, guppies, angels, tetra's, mollies, platties. I also have a few Cory's for a bottom eater. Thanks. Katie.