The only place I can find the desert gobie for sale (Karmafarmaquatics.net). In her salt guide she calls them light brackish. Says to use 4-6 tablespoons salt per 10 gal.(that sounds like alot of salt) I also have read other places that they are fine in freshwater. I will not put them in with Knight gobies, since they could turn into fishfood. I could put them into my freshwater tank if it is realy fine to keep them in freshwater.