Freshwater puffer

Fahaka Puffers are freshwater. They grow very large though and require an aquarium around 125 gallons.
 
Green spotted puffers are FW, but they do best in slight brackish. So, they are good for a FW setup.(in a species only tank) And only get to a max size of 3" to 3 1/2".
 
green spotted puffers require full on sea water conditions as adults.

they are not freshwater
 
GSP are not freshwater. I wouldnt trust a tripod website, someone probably just did that page themselves with who knows what kind of source for info. A good source, however, like linked above, is the puffer forum. Look at the GSP info here: http://www.thepufferforum.com/forum/ug.php/v/PufferPedia/Brackish/T_Nigroviridis/
Most folks on TPF will say to start them out in brackish, and as they mature acclimate them to full marine.
 
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