Green Spotted Puffer questions

[something_fishy]

I hope someone knows the answer to this.
My green spotted puffer seems a bit mentally challenged. He goes in the corner and goes up and down, up and down, up and down and so on. He eats live snails like there's no tommorrow and he likes frozen bloodworms. He goes to the bottom at times and turns a dark dark shade, almost to a grey/black and then when he gets up again hes a nice bright green with a white underbelly. The water parameters are as such:

ph 7.5
salinity 1.005
temp 78 deg
nitrites and nitrates ok
ammonia none
live plants
tank mates mollies, guppys, goby's
double filtration (2 filters) water crystal clear

Is he lonely? Are the water parameters correct? Should I raise the salinity? Or, is this normal for a puffer.

The other question is, can I put a figure 8 puffer in with a green spotted puffer???, both the same size of course.

 

[tyler]

"pacing" around the tank is common. is there anything in the tank he can explore (driftwood, plants, clay pots, pipes)? that may cut back on the pacing.

gsp's colors fade when they sleep, and they sleep on the bottom. no need for panic, probably just a defense mechanism. mine blends in so well when he's sleeping that i someimtes check around the outside of the tank (he jumped once, scary)

how large is the tank? that would be the deciding factor on adding the f8.