Purchased a 29 gallon freshwater tank 5 weeks ago. Currently have 4 platies and 1 molly along with 5 or so newly born fish. Noticed an ammonia spike yesterday to about 3.0ppm so did 25% water change with API quick start and stress coat. Re-checked today and ammonia is at about 1.0ppm. We have lost 2 platies since the start of the tank for an unknown reason. Tank appears healthy but we also have another fish now spending a lot of time sitting at the rock on the bottom. Not sure what’s going on or how to stop/resolve the ammonia issue.