Hi everyone! I currently have a 5 gallon tank. I've had it a little over 2 months now. I purchased it at my LFS with all the essentials needed. Per the LFS, I bought 5 tiger barbs to cycle my tank. After further research, would have opted for fishless cycling. The tank took about a month to fully cycle. At which point pH was between 7.4-7.6, ammonia and nitrite were at 0 and nitrate between 10 to 20. In the process I slowly planted my tank. All my tiger stopped eating within that first week and one by one started to die while cycling, as the store advised me it would happen. Only one made it to the end of cycling but then died off. Once he did I bought 10 ghost shrimps. They were doing well for the first few days. Eating everything and keeping the tank clean. Then slowly one by one started dying and/or the bigger ones would eat the smaller ones until there were no more. I then bought 10 more and three fancy guppies and then same thing happened to the shrimp. They slowly started dying. All throughout the water parameters were fine. I kept and record of all my levels as I do one every other day. Then one by one my guppies started dying and I only have one left and 3 ghost shrimps. I have no idea what to do. One of my plants is starting to die off too while others are growing very nicely. Really discouraging to see all your hard work and patience not pay off. My current levels are: pH 7.4, ammonia 0, nitrite 0, nitrate 20. Temp between 76-78° F. I have a filter with a gentle flow, light aeration by an air pump, heater and led light. I always treat my water when doing changes, which I do once a week to keep nitrates at 20 or less. What could I be doing wrong? If you have any questions, I'm more than happy to answer them. Thanks!