New to the forum but really need some help. I have a pest that is destroying my young lettuce plants in my aquaponics system. The young are sucking sap from the underside of the leaves which causes some kind of virus or black spotting. The adults are living in the coir of the system and are blackish, soft bodied and move very fast. I have plenty of pictures in the link. Also have some green gnats are are less of an issue. Thanks for the help!

Here is a link that might be useful: pests