Okay so I ended up getting the Dwarf Puffer yesterday. It was the tiniest one in the store, he is just barely a centimeter long. I say he but I am not sure of the sex yet, she could be a female or just hasn't developed the male markings yet.
Anyways I fed it for the first time today. He got two big microworms and small one at the end. I took a video of him eating his second worm.
Here it is. He is such a cutie, but I am not sure what to name him since his sex is a mystery :/