Seahorses will flirt with as many as 25 potential partners in a day, and about 37% of seahorse sexual encounters are same-sex acts. Many species of seahorses form pair bonds that last through at least the breeding season. Some species show a higher level of mate fidelity than others. However, many species readily switch mates when the opportunity arises. H. abdominalis and H. breviceps have been shown to breed in groups, showing no continuous mate preference.
The male seahorse is equipped with a brood pouch on the ventral, or front-facing, side of the tail. When mating, the female seahorse deposits up to 1,500 eggs in the male's pouch. The male carries the eggs for 9 to 45 days until the seahorses emerge fully developed, but very small. Once the seahorses are released into the water, the male's role is done and he offers no further care and often mates again within hours or days during the breeding season.