Most seahorses are considered predatory fish, and secondary consumers. They don't have much high risks of predators but do still need to be on the lookout.
Seahorses do mainly live on their own but, if not they live in herds.
Two limiting factors of seahorses are they don't have any teeth or a stomach so, food immediately passes though them. They have to keep eating almost constantly to stay alive.
Another is, a lot of People(mainly in Africa) use seahorses in Medicine or even eat them.