The puffers typically offered in stores are -
Figure 8 puffer
Green Spotted puffer
Ceylon puffer
South American Puffer
Congo Puffer
Fahaka Puffer
Mbu Puffer
Irrubesco puffer
Lorteti puffer
Fangs puffer
Fahaka
etc
Only the top 3 are considered brackish, and the GSP and Ceylon is considered to need marine conditions in adulthood. There are plenty more puffers available that I haven't listed here that are freshwater (or marine) also, so to say brackish would increase the options is untrue.
For tanks of 30g and less you are looking at -
"Auriglobus modestus" - The bronze puffer. This fish would have plenty of room in a 30, but they max out at 4". I think this is one of the few puffers that is piscovorious, but I couldn't be sure.
"Carinotetraodon irrubesco" - the red eye red tail puffer - These fish max out at 2 inches, and are shy.
"Carinotetraodon lorteti" - Red eye puffer - Same as above
"Carinotetraodon travancoricus" - Dwarf puffer. They max out at around an inch, and are great fish, but I doubt it's what you're looking for.
"Colomesus asellus" - South american puffer. Max out at 4" and are mostly timid enough to cohabit with other creatures.
"Tetraodon cochinchinensis" - Fangs puffer. Max out at 4" also, and are quite often shy fish.
"Tetraodon Miurus" - Congo puffer. Gets up to 6inches, very aggressive, but as it is an ambush fish, won't swim around a whole lot.
"Tetraodon palembangensis" - - King kong puffer. Also an ambush fish.
"Tetraodon suvattii" - Pig nose puffer. Gets to 6 inches, but doesn't swim around a whole lot.
Hi everyone, I am Julia live in Isle of Man, for all you who are "bikers" is the Tetraodon palembangensis, the Congo puffer, I have one can't find much info. about them, i.e. male/female, breeding if possible. Any special dietary needs, do they also need crustacians for their teeth??
Please will someone let me know, and how do you send in photo's fish/tanks etc., I also have two large Tiger Oscars, hand fed.
Please you guys, answer P L E A S E???????
Those are the freshwater puffers suitable for 30g. For bigg than that, you're looking at
"Tetraodon lineatus" - Fahaka puffer, needs 125 minimum, grows to 20" and very fast
"Tetraodon mbu" - Mbu puffer/Giant puffer, needs 150g+ in adulthood, these guys are enormous.
Hope that was some help.