Formed by bassist Jack Casady and guitarist Jorma Kaukonen of Jefferson Airplane, Hot Tuna plays a distinctive style of acoustic and electric blues. The lineup has evolved constantly, but Casady and Kaukonen always have been at its core and, despite a brief hiatus in the late 1970s, Hot Tuna has performed thousands of concerts and released more than two dozen records. “Steady as She Goes,” Hot Tuna’s first studio album in 20 years, was released in April 2011, and a new live DVD is on the shelves. The group is playing shows with guitarist and former Bob Dylan bandleader G.E. Smith, who once fronted the “Saturday Night Live” band. Hot Tuna performs at the National on Monday, June 25, at 8 p.m. $20-$25. 612-1900.