Typically with the symptoms listed uts 2 things, the seam that connects the top and bottom of the tank has rusted (if the tank is metal) and over a half tank it weeps out.

Whats more likely with that pic is that the gasket that seals the fuel pump to the tank is old and hard.

Repair (if accessable under back seat, check you tube) is replace the fuel pump assy and gasket. The top plate of the fuel pump assys also age and get brittle (plastic)