Seahorse
Like almost all other fish species, seahorses do not take care of their young after birth. Infants are susceptible to predators or ocean currents which wash them away from feeding grounds or into temperatures too extreme for their  bodies. Fewer than 0.5% of infants survive to adulthood. This is why litters are so large. These survival rates are actually fairly high compared to other fish, because of their protected gestation. This makes the process worth the cost to the father. The eggs of most other fish are abandoned immediately after fertilization.