In general, any small seeds that you would sow directly into the ground can be sown directly into a media-based aquaponics system. Although with these lightweight seeds it is possible that they will be carried away with the ebb and flow of your water through the pipes, so you may decide to broadcast additional seeds in case a few don’t make it to germination.  We have found that larger seeds that you would directly sow in soil (for example, beans, peas, cucumbers) don’t germinate as well within the media bed. For these we recommend using starter plugs such as Rapid Rooter, Rockwool, or coco coir plugs.