I'm including a link that I found that says Barramundi is actaully Asian Seabass. Perhaps that will let others who know about Asian Seabass tell you if it is feasible in ponds and compare it's flavor to local species.
http://pdf.gaalliance.org/pdf/GAA-Boeing-Aug00.pdfFrom what I can quickly gather from this, they will grow in freshwater, but not reproduce because of it. As stated "but must be placed in saltwater (28 to 35 ppt) prior to the breeding season to enable final gonadal maturation."
I wonder if this is needed everytime to spawn, or just once and they are forever able to spawn?