Molly fish and platies can coexist in the same aquarium, as they have similar care requirements and temperaments. However, it's essential to ensure a well-maintained aquarium with suitable water conditions and space for both species. Keep an eye on potential breeding interactions, as mollies and platies may crossbreed, producing hybrid offspring called "mollies." If this is not your intention, consider keeping only one species or separating males and females to prevent hybridization.