I have been trying to get my tank stable for two weeks now and have finally achieved 0 ammonia. The only time I had an ammonia reading above 2ppm is when I tested the water after noticing a strange smell in the tank. I get back from vacation and the ammonia is at .5ppm after three days of my not there. I change the water and a day later the ammonia is gone. Fast forward a few days and my gourami and Buenos aires tetras are getting very aggressive. All my zebra danios are the best eaters, breeding, and happy darting around in their school of six. The next day there are five zebra danios and a skeleton at the bottom of the tank. I wonder if it was the gourami who is four times larger or stress from the previous ammonia that killed the fish. We may never know, but what do you think?
