Saw you had no response, I'm not an expert by any means, just did some googling.
Looks like 30g per puffer is about normal for greens. As far as SG
, I'll quote a site:
"First of all, they are NOT in any way fresh water fish and cannot be acclimated to fresh water long term! They will die after a year or two. They should live 20 years! They are high end brackish water or marine fish. They can start in low end brackish (sg
. 1.005) but need to be raised to around sg
. 1.010 by the time they are 3" and sg
. 1.015+ by the time they are 6". I would recommend a bit higher though."
Source: Green Puffer Profile, with care, maintenance requirements and breeding information for your tropical fish
"I suggest keeping GSPs at low-end BW when juvenile <2", (in a specific gravity, or SG
of 1.005-08), at 2-4", medium BW (SG
1.010-15) and adult >4" SW