Green spotted puffer and figure 8 help!

Question

I want to get a green spotted puffer for sure; but i'm also very tempted by the Figure 8 Puffer. I know that green spotted ones can get to like 6 inches, and figure eights only about 3 inches. I now have a 30 gallon aquarium that is all set up brackish (a specific gravity of about 0.012), but by the time these fish get to adult state, i am willing to upgrade to a 45-50 gallon. I know the size difference is big, but do you think they could live together?

Answer 1

I had both in a 55 gal. and they didn't get over 2 inches.  I think if they are the same size when you get them you should be fine.

Answer 2

no.. the GSP would eventually need  fully marine water (1.020-1.025) and the F8 is a low end brackish (1.05-1.010)

not to mention that 40-50 gallons isn't alot of room to house to puffers peacfully..