No they do not. Only mammals and birds hibernate by changing their body temperature, breathing, heart and metabolic rate. Sea horses are unable to do so and hence, do not hibernate.
After years of debate, scientists have now finally confirmed that seahorses are indeed fish. In fact, the title of seahorse is given to over 54 different species of marine fish in the genus Hippocampus. The word “Hippocampus” comes from the Ancient Greek hippos meaning “horse” and kampos meaning “sea monster”.
Seahorses breathe using gills, have a swim bladder to control their buoyancy, and are classified in the class Actinopterygii, the bony fish that also includes larger fish like cod and tuna. Seahorses also have interlocking plates on the outside of their body which covers their spine made of bone. Although they do not have tail fins, they are equipped with 4 other fins, one that is located at the base of the tail, one under the belly, and one behind each cheek.