Is a porcupine fish mammal?

No, a porcupine fish is not a mammal. It is a fish that belongs to the family Diodontidae, which is a group of bony fish known as porcupinefishes or burrfishes. Porcupine fish are found in tropical and subtropical waters around the world. They are characterized by their spiny skin, which can be erected when the fish is threatened. Porcupine fish are not mammals because they do not possess the defining characteristics of mammals, such as mammary glands, fur, and the ability to give birth to live young.