You already have these fish plus the barbs? What tank are these in?
Could you please update your aquarium info so we have current information. Thanks.
Those aren't mollies....those are rosy barbs. I'm not sure about their ability to get along with tiger barbs but I do know they need a much larger tank. Rosy barbs can grow up to 5 inches.
Is there any way you could return the new barbs?