Hi Ron.
The Humpbacked puffer, or Black River puffer - Tetraodon palembangensis is a FW species, reatively peaceful (for puffers), will have territory disputes with others of the species, but if it is a spacious tank it's usually nothing serious. They are not a very active puffer, preferring to hide in a cave until it's time to eat. Like most puffers they eat live and frozen meaty foods: cockles and mussels, earthworms, snails etc. They grow to about 8" and prefer hard alkaline water, between 75-80 F with lots of plants and caves for cover.
They should be kept with larger tankmates as they have quite a large mouth and have been known to prey on smaller fish (and take chunks out of some of the larger ones). I would try to acclimate back to FW as soon as possible, but if you have to keep it with the GSP's you may want to set up some type of divider to stop any aggression from the GSP's or retaliation from the palembangensis
