Only from my reference literature can I offer any information. Between"Aqualog" and "Brackish Fish", it seems that the Mangrove Jack and the Emperor Snapper are encountered in waters with SG 1.012-1.018, but will not tolerate low salinity at all. Though this may only be at the juvenile stage. Hopefully this will at the least give you a starting point.
Sent from my C771 using MonsterAquariaNetwork App