Unlike some fish species that can change sexes, porcupinefish (Diodon hystrix) are dioecious, which means having the sexes in two different individuals. Because of the behavior of Spike and Fugu, we believe them to be male and female, although it's not possible to determine their sex simply by their appearance because they are not dimorphic (males and females visibly different).
Porcupinefish belong to the Diodontidae family, which also includes balloonfish and striped burrfish, both of which we have in the Giant Ocean Tank. Their most obvious characteristic is the presence of long spines that become erect when the fish inflates itself after feeling threatened, an ability that all pufferfishes possess. Their diet consists of hard shelled invertebrates such as sea urchins and crabs. Spike and Fugu are trained to come to the platform for their food, live crabs being their favorite. Here's a video of them swimming off into the sunset together:
Maybe they will get each other chocolate covered crabs for Valentine's Day!