Blues suffered their fourth successive defeat after goals from Toumani Diagouraga and Paddy Madden helped Fleetwood to a 2-1 win at Roots Hall.
Phil Brown’s side struggled to apply any pressure on the visitor’s goal as Uwe Rosler’s side went close in the first half with a Devante Cole header that cannoned off the crossbar.
Southend started the second half much brighter but were undone by a loose pass from Anton Ferdinand that lead to Diagouraga scoring on his Cod Army debut.
Minutes later and boos began to ring around Roots Hall as Paddy Madden got on the end of a Kyle Dempsey flick on to muscle his way through and score past Mark Oxley for Fleetwood’s second.
Blues did manage to make a game of it late on when Michael Kightly’s deflected effort looped into the net, but it was too little too late for Southend as they fell to their eighth defeat in nine.
The defeat leaves Southend staring down the barrel of the bottom four with just two points now between them and the drop zone.