upgrading my tank

i have a 60l biorb with 2 giant danios, 4 neons and about 6 silver molly fry(1 month old) i have just bought a fluval roma 90 and have set it up i have added the filter from my established biorb and added a rock ornament which im told also carries the good bacteria. when can i add my danios to the tank, thanks

A small aquarium like that should cycle in a few weeks, maybe less because of the established filter elements and decorations. Also try adding a small amount of flake food every other day. You will know the tank is cycled when it measures no ammonia several days in a row. Remember that you're dealing with a small capacity, closed system that will have a maximum biological load. That means you need to keep up with weekly, partial water changes and avoid over feeding.