Hi guys, so I bought a male halfmoon betta fish on Saturday from Petco. He seemed pretty good--fins still intact, his all-red coloring was very vibrant, no cataracts, and a good level of energy, considering the small cup he was in. He also looked young. He clicked with me. So I took him home. When I put him in my 10 gallon tank I did some water tests. Ammonia tested at 0.5 ppm. That was strange, because before this betta, the tank was empty for months--the only living things in it were plants--and the tank is a couple years old so it is obviously cycled (nitrites 0). So anyways, after seeing the ammonia I did a 50% water change (with distilled water, the general hardness was insanely high, although that also cut down my KH to almost 0 despite having crushed coral in the tank) and brought the ammonia down to 0.25 ppm. Then I did one again the next day but ammonia stayed at 0.25 ppm. Okay then, I figured I'd do another water change soon and treat the water with Prime, which I still have to buy. Throughout the past couple days, the betta seemed to be okay. He wasn't very excited or erratic, but he didn't seem sickly either, although he did sleep on the bottom of the tank during the day on a few occasions. And he was eating. He wasn't super excited to eat, but he ate without any issues. Then today, after just three days of having him, I got home from work and found him dead--nose down in the gravel, wedged between a java fern and the glass in the front left corner of my tank. I was bummed. I hadn't even settled on a name for him yet. He was a beautiful fish. But I figured that there was no sense in dwelling on it, so I scooped him out and tested my parameters. Here they are: GH 60 KH somewhere between 0 and 40, closer to 0 pH 6.5 Nitrites 0 Nitrates 20 Ammonia 0.25 Phosphates 0.5 I also found this metallic flaky looking stuff around his gills when inspecting his body. I would have attached a picture of it but for some reason the image upload keeps failing. If I can get it to work I will post it later. Could he have been sick right off the bat? Maybe it was velvet disease? Or was it something I did? Was ammonia too high? Did I do water changes too quickly/drastically? Did the change in hardness kill him? And how the h*** is there ammonia, nitrates and phosphates in my tank when I didn't even have fish in it for months?? So many questions, I'm so confused. Can you guys help me out?