Budgie,I believe these Giant freshwater stingrays are only found in freshwater.Very little scientific study that has been carried out on this species not a lot is known about these monsters ,hopefully we will be able to gain a better understanding in the coming months..With regards to the weighing of such creatures I feel the vulnerable status afforded Giant freshwater stingray by the IUCN is reason enough to release these creatures with the least disturbance and stress.It is the fishsiam teams preferance to take measurements and photographs before releasing these monsters.Our recent lump was captured on video which I will soon be releasing. I have enclosed a picture of our latest Giant freshwater stingray capture by Japanese businessman Koto-san with the assistance of my partner Wuttichai Khuensuwan 'Boy' after a protracted battle lasting almost an hour from the tidal Ban Pakong.
I am sorry for the time of my response and look forward to future contacts.
P.S check out wildlifeextra.