Have you been doing water changes with similar temperature water and using dechlorinator?
Do you know your water parameters?
General Hardness / Carbonate Hardness
/total dissolved solids
Have you successfully kept fish before? Know about the nitrification cycle?
If you need more info, check the article link in my signature which explains many important and helpful things for fish keeping.
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves