Hippopotamus, sea dragon and hippopotamus belong to bony fish. Hippocampus is named after its head resembles a horse's head, but interestingly, it is a strange and precious small fish that lives in shallow coastal waters. It belongs to Hippopotamus of Hippopotamus, with a flat head and two nostrils on each side. The head and trunk are at right angles, and the chest and abdomen protrude. It is composed of 10 ~ 12 bony ring, generally about 10cm long, with a slender tail and four sides. There is a pouch on the ventral surface of the male hippocampus, in which eggs hatch and can reproduce for 2-3 generations a year. At present, the artificial propagation of hippocampus has been successful. Hippocampus is a valuable Chinese medicine with high economic value, which has the medicinal functions of strengthening the body, tonifying kidney and strengthening yang, relaxing muscles and tendons, relieving inflammation and pain, calming the nerves, relieving cough and asthma. Especially for the treatment of nervous system diseases. Hippocampus is not only mainly used to make various synthetic drugs, but also can be taken directly to strengthen the body and treat diseases.

A small warm marine fish belonging to the family Syngnathidae of the order Syngnathidae. The body is wrapped in the armor formed by the bone ring, the tail is bent forward and can be rolled up, the head is horsehead-shaped, forming a certain angle with the body, the kiss is long and tubular, and the mouth is small. A dorsal fin consists of fins. The eyes can move independently. Different body types, about 4 ~ 30 cm long (1.5 ~ 12 inch). Poor swimming ability, generally living in coastal areas, seaweed or other aquatic plants, crawling around with their tails. Keep upright when swimming, and use each fin to push and change the air content in the swim bladder to float or sink. Feeding on small organisms inhaled rapidly in the mouth. The male fish carries the fertilized egg, and the female fish lays the egg in the pouch at the tail of the male fish until it hatches. When the young fish hatch, the male fish wriggles and releases the young fish from the only opening of the pouch. Hippocampus is a rare aquarium ornamental animal. Its species is the sea horse, which is smaller than other species. European brown seahorse; Pacific hippocampus (H. kuda); Australian medium-sized white seahorse (H. whitei).