That looks like a Blue Gourami. Gourami can be rather aggressive so placed with a nervous fish will intimidate them. They also need generally to be the only Gourami in the tank.
How big is it compared to the new Silver Dollars? What size tank? Is there lots of cover to hide? Silver Dollars are a nervous fish and likely need bigger groups and for sure need places to hide. Will eat live plants too by the way.
Good luck. You may need to re-home something or return something depending on what other members say...
Have a look at the Fish Profiles at the top of the page and read about both species.
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