Mollies in frshwater

[Bogben14]

Do mollies need brackish water or can they be kept in a freshwater tank?

 

[CatoeSc]

Do mollies need brackish water or can they be kept in a freshwater tank?

Fresh is fine. You can add aquarium salt if its all mollies, but its not required. I have 3 black miles in my planted community and never add salt (anymore), and they're fine.

 

[Fishfur]

You are correct that mollies are brackish water fish in nature. But they adapt very well to fresh water, and most are raised and sold in fresh water. So there is no need to be concerned about the lack of salt. If you only have mollies, sure, you can add some. But I think you also were asking about Otos ? if so, they cannot tolerate salt, so don't add any if you have catfish of any kind.