Hmm, I've never had puffers, so I don't know anything about them... I think at least some species are brackish water fish, so it'd be best to check first. Maybe do a search or ask in the oddballs section?
As far as the loaches go, my clowns ate snails when they were about 3-4in. Don't know why yours don't.
morrgan, thanks for reply. i must feed them too much. lol.
i have tried the spotted puffer, he is called boris and he has almost eaten all the snails : puffers can be kept in fw when they are small.
My 4 clown loaches are 2.5 inches long. They usually only get to 6 inches in the aquarium, however in the mighty big aquariums, they get to about 12inches long.