u/DueHelicopter4189

I set up a 2 feet planted aquarium 7 weeks ago. Added 10 Epis Rasboras about 8 days ago. 5 of them have perished since then. I suspect ammonia is the culprit. I don't have the kit and was relying on the bacteria and the ecosystem to keep things under control. I did use a bacterial starter. Where did I go wrong? What can I do to ensure such things don't happen in future? Also, please feel free to share your take on the design. No fertilizer, non CO2 setup. Added a DIY cooling fan today.