When threatened, the spiny puffer inflates its body with water or air, which causes the numerous long spines covering the body to be erected. The inflated body and the sharp spines make it difficult for a predator to ingest the puffer. After the danger has passed, the puffer slowly deflates itself and resumes a more normal shape. It is known for being aggressive and may nip tank mates. It is important that it eats shelled inverts like raw shelled shrimp or shells as it needs to keep it's teeth worn down.