Honestly I would suggest the A. Modestus. If you have the tank densly decorated you could do a few in there. The good thing about this species is that they stay small at around 5" but still big enough to actually enjoy, and they also are completly FW. I think their best quality is that they have that "saltwater puffer look" to them. I had one and it was one of my favorite fish. It hand fed and everything. I had to get rid of i because I moved and my fiancee was so upset cause it was her favorite fish.