Hello Rivas and Welcome

to Fish Lore. Breeding Silver Dollars can be difficult. They like large leaves to lay their eggs on. However, they love to eat plants so I would suggest fake ones. Raise the temperature in your tank a couple of degrees (as this tends to start the mating process in most species of fish). Silver Dollars are not aggressive towards others even during spawning so they eggs could very well be dinner for other tank mates. Don't be surprised to see the Silver Dollars turn black during this time. They will chase each other all over the tank, swim around in circles then get side by side and just quiver. It's an awesome sight. Sadly I've never had any eggs to survive though.
Best of luck and I hope you enjoy the site.
Ken
