can Monodactylus argenteus and sebae live their whole lives in brackish water or do they need to be acclimated to saltwater when they are fully grown? if kept in brackish water will they stay happy? also what is the normal size for one of these fish? i know in the wild they can get pretty big but fish in an aquarium tend to stay smaller. so any ideas on how big that usually get in an aquarium? Thanks all.