my green spotted puffer lives in fresh water and hes nice and happy
the old chinese guy that helped me said this when i bought him:
old chinese guy:are you putting this fish in community tank?
me: no i set up his own ten gallon, is that good enough?
ocg: oh yes, very good, is it brackish?
me: yeah i put a little salt in it, i heard it wa-
ocg: before you put him in there, change the water completely, he will turn black and get sick if you put him in brackish water.
me
h...ok i will, but i heard that they are brackish...(standing there with puzzled look on my face)
ocg: oh, some are. these were caught in a fresh water stream, no where near brackish water. they were born fresh water puffers.
me: oh.......cool, thank you for that tidbit of info
ocg: enjoy your puffer
when i got home i tried to put him in the brackish for a while(because curiosity killed the loach, and im usually not one to go against the word of an old strange chinese man anyway, but i had to see) and within 2 minutes of being in the brackish water he turned so dark green that he was almost black! i put him in a 5 gal bucket as i changed his water and thanked the old man in my head. my puffer loves his freshwater!