Green Spotted Puffer (tetraodon Nigroviridis)...

[bogwood]

Quoted from the net:

'Born in Freshwater, as they mature these Puffers migrate through estuaries/streams between Freshwater lakes and the Ocean, to live out their adult lives in Saltwater. Although these fish are happy in Freshwater (as juveniles), when adult, they will grow larger, have brighter colouration, suffer less disease and live longer in higher salinities...'

...So how long does it take for these Puffers to reach 'adult' status and therefore need a Brackishwater set up?...

 

[Fella]

Typically it's encouraged that they're in fact kept in brackish in tanks, and then migrate as they get older to full marine, from what I can gather they're sold in fresh and then gradually salt is increased at regular intervals from there.

http/www.pufferlist.com/puffer/puffer2.php?puffid=15

There's a great page on them.

 

[Pufferpack]

I don't know if there is a hard and fast timeline for switching from FW to BW to full Marine. Your best bet would be to acclimatize them to BW as soon as you get them from the LFS (if they were kept in FW) and they should be fine there for a couple years before going up to marine. I believe they are safe to go into marine once they reach about 3 inches or over.

 

[love cichlids]

The Green Spotted puffer does best in brackish water to full marine (as adults). At 1” they should be in a SG of 1.004, at 2” an SG of 1.010, at 3” they should be an SG of 1.015, at 4” they should be in an SG of 1.018, at 5”-6” an SG of 1.022-24 (full marine).

This is what I found when researching before I got mine last yr. I asked them at the store what their salinity was and mine was about the same as theirs when I bought my puffer. Go to a reputable store for puffers, some stores have them but don't know much about them and give you wrong information. When shopping for a puffer go about an hour to 1 1/2 hrs after they open, that should be around the time they feed them so you can see which one eats well, big round belly full of food. That is how I picked mine out and she is still going strong, picky eater but still cute and healthy.