First, enter into an interactive node:

$ pjsub --interact

You may check available modules:

$ module list

Probably gcc can be used by default. To use g95, you may need to load it:

$ module load g95

gfortran may not be supported.
When you build FVCOM, you need to enter into an interactive node and then compile all the components using gcc and g95:
METIS can be compiled using gcc with optimization of -O3.
netCDF should be compiled using gcc and g95.
When building FVCOM, you need the original mpi.h that should have been deleted when compiling with Fujitsu compilers.