I cycled my 10 gallon (https://www.petco.com/shop/en/petcostore/product/glofish-glass-aquarium-kit-10-gallon) tank for about 3/4 weeks and saw the spikes of nitrites and ammonia then both hit 0 and the nitrates were at a pretty good level. From what I had read, it seemed like the whole cycle was done so I went ahead and bought 5 glofish tetras last Wednesday. For the first 4 days or so, they were perfectly fine. They were eating, they were active during the day, chasing each other around in a friendly matter. I had the glofish lights on from about noon to midnight. I assumed things were going well so I even bought 3 cherry shrimps and a nerite snail for the tank on Saturday. On Monday, I realized that my fish were staying in one area in the middle of the tank and just staring blankly and they were not eating anything I fed them. I did realize that the GH was a bit high, 200ppm and that the KH was at 0. I did some water changes and added the quick start stuff for some extra bacteria and to get rid of the chlorine. I also cleaned the inside, got rid of any plants that looked even remotely dead and got rid of the air tube to my volcano since it looked a bit dirty. I waited a day and yesterday, nothing had changed. Today, a week since I bought them and two since the activity change, one of my glofish tetras died. It was inactive like the others but slowly started to gasp for air at the top and then just laid there and went upside down. What could be the cause of this, what should I do? I am new to having a fish tank, and it has been frustrating since nobody at the store told me about cycling so I already had to go through a few fish before I redid this tank.