They must not be a true grouper. ??? Groupers are born and raised in the ocean. It's like calling a freshwater redtail shark a real shark, am I right??? or am I wrong???
Unfortunately you are wrong,
the groupers are part of the family Serranidae, almost all are salt water but a few are brackish, some spend part of their time in freshwater, and one is a freshwater to brackish water fish and (as far as I know) has never been found in full seawater. It is the white-dotted grouper (Epinephalus polystigma), it is an attractive fish that I have never seen sold, pity, becuase it would be perfect, getting to a max of just under 16" and breeding in brackish and freshwater as small as 8" long. here is a picture by Randall.
The Bumblebee grouper is a huge and rather unattractive fish as an adult and has been recorded at around 10' long and 800 lbs. Keeping them in freshwater lowers there resistance to disease and I have found no records of them reaching any where near maturity in FW, they seem to requie more and more salt as they age and by the time they are 4-5' long (in the wild) they are solitary hunters near reef systems. IMO they are not a good choice for private fish keepers.