figure 8s vs SAPs

Have been on a puffer kick here and there for awhile now. I wish I could get a huge fahaka or even MBU, but that isn't even close to reasonable. I would like a popular, active, medium size puffer but can only come up with these 2 as being suitable to my means. Yes, they are small, but I can't think of anything about 6-8 inches. My Rough ideas are:

option A) 20G long - (1) figure 8 puffer, (3) bumblebee gobies, 1.005 SG
*I read somewhere that figure 8s don't Have to be brackish. is there any truth to this??? Also, can they get bigger than 3"?

option B) 20G long (don't know if this is too small) - (3) SAPs, (1) BN pleco
*my main concern is that I keep getting different information on SAPs. how big do they actually get??? some sites say no more than 3 inches, some say 5.

Any suggestions to add or help with these ideas, or even new ideas?

 

F8s need to be brackish for long term health. They may survive for years in Freshwater but they won't live a full healthy lifetime in it. This man has kept them for as long as 18 years and 15 years was very common.

My older F8 is around 4". He was purchased full grown 3 over 3 years ago and hasn't grown any more in that time.

 

My older F8 is around 4". He was purchased full grown 3 over 3 years ago and hasn't grown any more in that time.

What size tank is he in?

 

What size tank is he in?

First 4-5 months a 29g. Next year a 46g. Last 1.5+ years a 55g. Other than the first few months he's always been kept at 1.005 SG and 50% WCs.

 

First 4-5 months a 29g. Next year a 46g. Last 1.5+ years a 55g.

So a setup in a 20L wouldn't suffice for the life of the fish, especially if he has tankmates?

 

A dwarf puffer would work and they're freshwater. You could probably have 4 in a 20L.

 

A dwarf puffer would work and they're freshwater. You could probably have 4 in a 20L.

The OP asked about Figure 8s and SAPs though. You could put a whole mess of dwrfs in there!