If not captive bred, then the only option will be live food, not brine shrimp. What do you have; what is the setup; have you seen them eat. Unfortunately, most wild-caught never wean to frozen and slowly starve.
What I do is use a sieve. I gather the bbs from the soda bottles I use to grow and enrich them in, then drop then in the sieve (using a turkey baster). Clean that under tap water, remove as much as that water as possible, then dump into the aquarium. The aquarium is low flow, so as a result the seahorses have no problems catching the bbs when they swim by. I do not believe that I have some second generation babies yet (I acquired the adults in March), but they are growing fast.
I have a made a (crappy) video of their mating dance:
Ok got it. Glad it is working out. H. Erectus need larger food so mysis shrimp are recommended. The article on seahorse.org is helpful too. Thanks and cool video!