Nice pair of erectus you got there!
There's two schools of though with raising the fry:
School 1:
Special dedicated rearing tank.
Kreisel flow system, which uses an old-school-fishbowl-with-flat-sides shape within a larger tank to allow for rotation of water to keep food suspended in the center with the fry and to keep the fry away from the surface.
Regimented twice or more daily feedings and waste removal
Very close supervision and multiple daily sessions with the tank.
School 2:
Let em go for it.
I know people who have been successful rearing them both ways. In fact one local shop owner tells me that all she puts in the small tank is a piece of live rock, and has just as much success as the folks who are doing the full kreisel-nursery setup.
Regardless, here's things to think about:
Flow should be slow.
Gotta think about them getting sucked into your filtration setup, so must adjust.
They need to eat.. a lot! Therefore, they need to poop... a lot!
Other fish will pretty much eat anything they can fit in their mouths, so seahorse fry need to be fairly self contained, with no predators around.
In general, just keeping them in your regular large tank would not allow them to find enough food, etc... by using a small rearing tank, especially with the Kreisel setup, they have easy access to the food they need to live and grow quickly.
To start with they really need live baby brine shrimp, then move on to rotifer, copepods, then onto mysis after a few months. You will definately need to be culturing live brine daily to keep them fed for the first few weeks.
There are many folks saying that the presence of copepods in the rearing environment directly affects the success of the fry,, but I havent seen a scientific study about it, only a whole lot of successful breeder saying that it's a good thing. Apparently even when young, they'll go after the smaller copepods, then by the time they get thru the brine and rotifer time, they'll start feasting on the larger ones.
Theres no hard and fast rules. You can do it super-scientifically, and apparently you can also have success in a purely natural way (well, as natural as a small piece of the ocean stuck inside your living room can be...).
If you'd like more info, diagrams of the kreisel setup (sent to me by Pete Giwojna, one of the most famous seahorse experts), or any more advice, let me know.
Just remember that many, if not most, of the folks who try to raise seahorses cant really do. The survival rate is naturally low, and most experts will say that it takes quite a few attempts at it to start becoming successful... some people are never able to do it. But if you get lucky, are VERY skillful, or just find the magic combination for that batch, you can get quite a few of them to juvenile, if not adult stages.
Good luck.
Feel free to contact me.