you'll have to dig some holes during the drier season to see if the water table has actually receded, if it is a muddy clay silt, or if you have sand. If the water table recedes to 8 feet down and you have sand, you can definitely try building some mounds for planting mangoes.
If you have an excavator you can basically build till huge rows, which gives you draining high ground and a water source year round for raising tiliapia, snakehead or gourami.