u/La_Dolly1234

We had glofish for years without issues. Then we bought a 10 gal tank. Bought a few more tetras (all tetras). My daughter decided to do a water change herself and added rocks (store bought) but forgot to rince them. They all died...except one. I did 4 partial (25%) water changes over a week and half. Then bought 4 more glofish yesterday. They all died overnight except for 1. So i have 2 fish left now, including our original one. What are we doing wrong?