Ok I started a new 3 gallon freshwater tank a little over a month ago, it has a filter and a heater. wster temp is usually between 74 and 78. I had 2 male guppies, a Mickey, and a female balloon Molly. The Mickey died within 2 days so I went out and bought another male guppy and another female balloon Molly cause I thought she was lonely. I had no problems for a month and then one of my male guppies died. Then about a week and a half later both mollies were dead one morning. I had done partial water changes a few times and had just done a complete clean, filter, gravel and all about a week before my male guppy died. I got the water tested And ammonia was high. I then did a 75% water change and my last 2 male guppies were fine. After about 3 days I took a sample of water to the pet shop again because I wanted to get another male guppy or two. The Ammonia was gone and everything else was in the safe zone. So I bought 2 more male guppies. They were fine the first night and all 4 guppies got along and hung out together. They all ate fine. Then this morning one of the new male guppies was dead and the other new one on the bottom barely moving, but the guppies I already had were fine and wanting to eat. I fed them and the one on the bottom came to the top but tail first like he could not keep his tail down. He could not eat and got himself down to bottom again and is almost dead. But my other guppies the ones I had are fine. I guess I will just keep the 2 but I do not know why the new ones died and I really wanted another one or 2 male guppies because I was told I could have up to 4 in that tank. I have read so many different things and am not sure what to do? Thanks