I cant get to my usual source to figure exact numbers for that tank but some options would be all species only:
- Pea or Dwarf Puffer - you could have a fair few in there! Though would need careful planning to break line of sights etc.
- SAPS - could be recommended but will say when I looked into same tank and species not very recommended as they are extremely active and need the tank length, also prone to need their teeth clipping.
- Figure 8's - need low brackish which isnt too much hassle on a freshwater aspect, very pretty puffer
-Irrubesco - Red Eyed Puffer - beautiful puffer need a good male to female ratio and these have been known to work really well in community setups (never guaranteed though), there are various species knwon as Red Eyeds - Irrubescos are known to be friendlier.
- Congo Miurus - only one and depending who you get can be bit inactive - gorgeous colours and pouty lips!
- Target Species such as Abei, hairy Puffer etc. Depending on dimensions some have managed to keep one or two together, though usually recommended loners. Hairies (Bailyeis) are fantastic!