Their maximized size is 18.5 cm, however at 12 cm they are sexually mature. The species is known to develop elaborate skin fronds and males have proportionally longer tails than do females. Hippocampus erectus is one of 44 species listed by the IUCN. It is considered vulnerable due to its use in medicinal trade and pet aquarium trade. Live trade is mainly per black market . The dried seahorses are ground and consumed in drink as a folk medicine for a number of diseases including asthma, alcoholism, thromboses, bronchitis, impotence, osteoporosis, heart disease, cancer, and rheumatism. This is especially true in traditional Chinese medicine. Threatened by being caught as bycatch in shrimp trawl fisheries and by being targeted for the aquarium trade. The preferred habitats of H. erectus is declining due to coastal development, pollution, destructive fishing practices such as trawling and increased sedimentation. Full monitoring of the trade of H. erectus was implemented in 2004, but it is dependent on traders’ declarations.