I have a 65G tall tank. Last Sunday I bought six rummy nose tetras, one tiny cory cat and a fire eel that was 5-6 inches long. I bought three clown loaches a few weeks back, and they are fine. The eel was pretty much dead Wednesday morning. He never ate for me, but I know that that can be common. I'm wondering what it is about my water that it didn't like. I posted a pic of all my water tests. I don't really understand the GH/KH, but I did the tests and posted how many drops it took to change to the right color. I do about a 30-40 percent water change every week. I am struggling a little bit with diatom algae, so I also clean off all the plants and rocks (outside of the tank). It's getting better. I started feeding mostly pellets now instead of flakes. Back on topic, a few months back I bought two dwarf gouramis, and five small rainbow fish (not sure of type, but they were tiny like danios with a pretty blue stripe down the length of their sides. The rainbows were all dead within 3-4 days, and the gouramis died within two weeks. I don't get it, because I have had three angels, 4 bosemani rainbows, 3 cory cats since last November when I started up my tank, and am thankful they have always been fine and healthy. I check my water all the time. Do you think its a ph problem or a water problem (too soft or too hard)? I just feel so bad for the eel. He suffered before he passed, and I don't know if there was anything I could do about it. He was healthy. I keep the tank temperature at 77 degrees. Sorry this post is very long - it's my first post, so won't have to explain everything again in the future. Thanks.