Salty Dog Tavern (1723 Connecticut Ave. NW (b/t R & S), Twitter, Facebook, Instagram, website) is set to open in the former Black Fox Lounge today, Tuesday, April 21st, in north Dupont Circle.  The lounge/restaurant will feature $4 specialty cocktails for its daily 4-7p happy hour; the spring cocktail list features $4 passion fruit sangria, blood orange mojitos, ginger margaritas, vodka strawberry lemonade, beer and wine and tapas. As Barred in DC has exclusively reported, this spot comes from the  folks who currently operate Alley Cat  Restaurant & Lounge in suburban Alexandria across from the Landmark Mall off I-395.