Their teeth are different as well. The Porcupine has fused front teeth while the Puffer has two separate teeth on each jaw. All Porcupine fish love to eat crustaceans, molluscs and any meaty food. Their strong teeth and jaws are designed to crush the shells of crabs and snails, so they are not good tankmates for invertebrates. They will readily accept earth worms, shrimps and crab meat.
Porcupines only inflate and extend their spines as a defense mechanism.
While they will accept some touching and hand feeding, do not pick the fish up in an attempt to make it inflate. This is extremely stressful to it. These bold fish have very interesting personalities and will definitely develop a relationship with their owners. In the wild, the Long-Spined Porcupinefish can grow to 20 inches but maximum size in an aquarium is 6 inches.