From What does the Green Rough-Backed Puffer Fish get its Nutrients?  
The Lagocephalus lunaris resides along the coasts and within coral beds. Down near the ocean floor is where they find their food. They are predators and they feed on mollusks and crustaceans. Sometimes this species will eat algae. This species is in the order Tetraodontiformes which literally means "four tooth" in Greek. They have fused jaw teeth but they are separated by a median suture, which gives rise to four distinct fused teeth. They use their jaw and teeth to consume their prey or to chew up vegetation.

 Image Located at Picasa Web Albums

Other organisms use the Lagocehalus lunaris to get the nutrients, but these carnivores have to be careful because this particular species of saltwater puffer is very poisonous!!!

Check out this Species' Reproduction!