The Pufferfish can inflate it self since it has a remarkably flexible & elastic stomach that can be filled with water. If the Pufferfish becomes scared when it is out of water, it will instead suck in air. A puffed up Pufferfish will be nearly spherical. Regardless of whether your Pufferfish is in or out of water, you should always strive not to frighten your fish. Every time a Pufferfish inflate it self, it risks dying since air can become trapped inside its body & prevent it from deflating.. Leave the wild in the wild..