I've read mixed things but are south american puffers (Colomesus asellus) strictly fresh or do they eventually need brackish conditions?
I agree.C.Asellus as far as i know has always been 100% F/W fish unless documents have been updated in recent years to say otherwise?
However T.Fluviatilis (AKA Ceylon Puffer) that looks similar is a puffer that requires high end brackish to marine as adults which maybe where the confusion comes from...
The Masked Shadow there are actually a lot more F/W puffers than what you listed including a few red eye species such as C.Salivator, C.Irrubessco and also species such as T.Miurus, T.Baileyi among others...
Fahakas are definitely fun puffers to keep, not too small and not overly large...