Yep, agreed. No snails. I have had some success dropping in MTS at night and then they will bury themselves before the puffers wake up so they could survive. I have 2 in a 5.5 gallon but I wouldn't put in 2 again just because they are constantly squabbling over territory. I also have 2 Amano shrimp and 12 RCS and they don't even care about them. Sure, they may eat shrimp lets but adults are safe. I also get tons of berried females so I know they're not stressed or anything. Just be warned that the shrimp lets probably won't be sufficient for the puffer and that you may need to offer live or frozen food in that case. I have a small blackworm culture that I feed my puffers with. Only 1 of the puffs takes frozen. A better option for your 20 long may be scarlet badis because the shrimp lets will be sufficient food for them and they stay smaller, which means they can't eat adults. I know Theresa had some scarlets, you may want to ask her about them. What kind of filtration do you have on the tank? They aren't really messy eaters but they do need better water quality than most other fish. This is a planted tank right? Puffers and scarlets do appreciate planted tanks to hide in and explore, and it will also give the shrimp a place to hide.
If you want to do DP's, go ahead! They are cool fish and really not that hard to care for. Only thing to watch out for is sicknesses really. Pretty hardy too IME. Hope this helped!
