I don't see any need to add salt for HRPs, convicts of FMs on a regular basis, unless your tap water is mineral free.
With the JDs you could go either way, I snorkeled with them in the Yucatan, and the Cenotes they inhabit there, were only a few hundreds yards from the Caribbean, so a bit brackish (like the video below), but there are also JDs from further inland where the water would be totally fresh.
Eden2
With the JDs you could go either way, I snorkeled with them in the Yucatan, and the Cenotes they inhabit there, were only a few hundreds yards from the Caribbean, so a bit brackish (like the video below), but there are also JDs from further inland where the water would be totally fresh.
Eden2