It varies. Some are nice as pie, and seem to work out fine in community tanks. Others are aggressive and/or fin-nippers and wind up being kept alone.
I'm not sure whether their behaviour depends on the tank and the fishkeeper; I suspect it does. My theory is South American puffers get bored easily and are very picky about their food, and so are more likely to turn nippy if they aren't "happy". In other words, they're like dogs or cats -- they need to right environment or they develop bad habits. One things I've noticed is that my South American puffer explores the plants and rocks and bogwood and other fishes constantly. It looks over every crevice and surface. This is exactly what puffers do in the wild: if you watch them, they are like little scanning machines, using their bug-eyes to explore fully their habitat. I suspect they're smart and inquisitive, and compared with most other fish, have a very low boredom threshold.
Besides their behaviour, my experience with this species is that they aren't as sensitive to water chemistry or nitrates as most other puffers. If you can keep other South American fish -- like neons or rams -- alive and well, then you'll manage these puffers fine. Settling them in can be tricky, but once they're feeding, these are probably the easiest of all the freshwater puffers to maintain.
One thing that is known about them is that they are schooling fish in the wild. Few people keep them in large numbers because they don't give them tanks large enough. Two or three specimens tends to be dicey, just as with any other schooling fish -- you get the problem of bullying. Single specimens are fine, but seem rather nervous compared with other puffers.
Cheers,
Neale
thanks. the only one i like besides the DPs (which i have) are the southamerican puffers(Colomesus asellus). are these guys hard to take care of?