Seahorses/Seadragons

pygmy seahorses is what I would do. A pair of them with a piece of live rock and a gogorian(sp)

Sea dragons will get too large, and I don't think they are legal to purchase. If you won't be able to provide live foods 2-3 times a day, I would go with a reef instead of ponies, with maybe shrimp or crabs instead. Ponies need to graze throughout the day (they have no stomach, just a long intestine, so no filling up and digesting later). In a larger setup, their diet can be supplemented with copopods, but in a small setup, they can easily eat everything pretty quickly. If you can setup a refugium that will flow into the tank (water pumped into the fuge, siphoning into the tank, so it would need to be level with the top of the tank), you'll have an easier time of feeding them and the benefit of additional water volume.

Will this be your first SW tank? If so, I would take it extra slow, and cycle, then keep the tank running for about a month without any fish, just to get used to keeping the salinity and temp stable. Same problem in a FW tank this size, but causes bigger problems in SW since the salinity swings can be rough on your inhabitants.

If you are really interested in a seahorse tank, there is a huge amount of info at seahorse.org.

Celura, yes what you are purposing is possible with pygmy seahorses. This just IMO and I'm a chicken so take it for what it's worth. It would be exceedingly difficult to start out with seahorses unless you want to give them a lot of attention. As has already been mentioned by OF.G. they have to graze pretty much all the time. On top of that they are pretty sensitive to water conditions," which can be hard to keep constant without a little practice". Most all of the wild one's have a pretty big load of parasites as well and sometimes they can be really hard to treat. Also the larger your s.w. tank is the easier to keep stable etc. They are really neat critters though and I've always been really enthralled by these fabulous critters. I just wanted to let you know what you're getting into but, I'm sure you've done lots of research. I'll quit rambling now. keep us posted .
hth
Chris
p.s
welcome to s.w. I know that you'll love it as much as we do.