Okay, that’s cool, too – it’s neat that someone is offering mollies for sale that have been converted to full strength saltwater. They would make good, hardy, inexpensive fish to cycle a new marine aquarium with, and if it was a dedicated seahorse tank, the mollies could remain in the tank afterwards, just as you are thinking of doing, Tamy.
That’s an easy mistake to make nowadays, confusing platys for mollies. Both platys and mollies are available in so many strains now with variable coloration and variable fin development that it’s difficult to tell a mollie from a platy from a female swordtail these days.
The mollie should work fine in your seahorse setup as long as you are aware of the potential algae problem, Tamy, so go ahead and give them a try as soon as you are done quarantining them.
Good luck! Be sure to let us know how everything turns out!
Pete Giwojna, Ocean Rider Tech Support