Molly And Salt

[Platy lover]

Do mollies really need salt? I have them in my 29 gallon along with a bristlenose pleco, a mystery snail, and a betta. I know pleco's can't handle salt.

 

[nmonks]

Need? No; in the wild they mostly live in freshwater streams and ponds (though with that said, natural, as opposed to introduced, populations are rarely far from the coast). But in captivity they do seem to be less prone to diseases when kept in slightly saline conditions. The reasons for this are obscure but may be related to nitrate and nitrite toxicity (which sodium chloride reduces). There may also be some benefits in terms of osmoregulation, especially if they are kept in water that isn't hard or alkaline. However you look at this question, the bottom line is that on average, Mollies are less likely to be sick if kept in slightly brackish water than freshwater, and conversely, sickly Mollies often perk up when moved into slightly brackish conditions.

You are right that your Ancistrus will not appreciate the use of salt. But the standard plecs of the hobby, Pterygoplichthys spp., not only tolerate slightly brackish water in captivity they are also very common in slightly brackish ditches and canals in Florida where they have become well established. Indeed, you'll probably find Mollies in precisely the same habitats!

Cheers, Neale

Do mollies really need salt? I have them in my 29 gallon along with a bristlenose pleco, a mystery snail, and a betta. I know pleco's can't handle salt.

 

[OldMan47]

Well put nmonks.
The case of water with low minerals or otherwise known to be quite soft can be a real problem for pet shop mollies. One way to add minerals is salt, but it would not be the best way with your other occupants. If you have soft water and snails, both the mollies and the snails would benefit from some added calcium carbonate. It will make the mollies more comfortable and will add minerals the snails use to build their shells. A way to get that is to put some crushed shell or crushed coral in the filter flow path.

 

[Platy lover]

I will try crushed shells