hi cloob,
i have never kept this species, but other pufferfish.
the species is not known to have crustaceans as its main food. on the other hand i would not dare to try it...

but the bigger problem is another one: i think its not so good to buy an animal to get rid of another: if you have too much snails in your tank, i think you should try to find out why they are so much...
what will you do, when the puffer has eaten all of your snails in a week or so? do you know that all puffers need permanent hard-cored food to trim their teeth? if they do not get snails, hard coral or something alike for a longer time, the teeth will grow that big that the puffer will die from hunger one day!

martin