Since this is your first try at seahorses, consider normal-sized like the majority of the horses at www.oceanrider.com. I've read that the dwarfs are more delicate (any disputes welcome, this is just what I've heard). It's also easier to keep a larger tank stable. Many folks over at www.seahorse.org keep their horses with a limited selection of corals. Thoes horse-heads are even breeding these guys. Helpful people.