Well, I started my tank about a month ago. I'm not really new to it though. I had a 10 gallon when I was younger and I was very lucky..however, my luck has started to change. . In my tank I had 3 corys, and 6 zebra danios with two snails..I was pushing it...well, the other day one of my danios died....and I just thought he was sick, since he was the littlest of them all...well, today...I came home from work and one of my snails died!...I did a water change, that's how I noticed it all....and I tested the ammonia levels...they were high..I'm thinking that is what killed them. I put ammonia clear tabs in my tank. I hope that works....Any help??