Can someone identify my puffer

[Cashimus20]

The local fish store sold this little fellow to me under the name spotted dwarf puffer. I'm pretty sure they sold me a GSP which is not cool because I spent time and money establishing what I thought was going to be permanent habitat for him in a 5 gallon tank. If it is a GSP he will outgrow his tank very soon and require gradual salinity adjustment until I have to completely convert to "marine" water. Someone please confirm my suspicion so I can return him before he requires a 40 gallon tank to himself!

 

[Brown Water]

Looks like what is sold at lfs in brackish as common name of green spotted puffers. Not a lot of exp with this family of fish tho so don't hold me to it.

 

[Alyxx]

Definitely a GSP. They are great fish, lots of personality.