I started this little tank in hopes of just having 3 -5 fish. But something odd has happened. I have a cory cat, 2 glass fish, all of those are doing fine. It is at the very end of the new tank cycle. So I went out and got 3 small guppies, 2 lyretails and one fantail. I got them on march 30 and in the last 12 hours they have all died. Anyone have any ideas what's going on? This isn't my first tank but it's been years since I started a new one. I have been using the Tetra brand startup, aqua safe, easy balance, and foods.