Katie -
Cohiba gave you a very good website for you to find out more about seahorses. You can also go to
www.reefcentral.com and click on forums then find the pipefish/seahorse forum that has alot of information.
I presume you have a wild caught seahorse that can some can have problems with, but my seahorses are wild caught and have success for over a year.
One thing that I didn't see included in the posts, is how is your seahorse housed? Did you put him in your main tank?
Remember seahorses like calm waters and need plenty of "hitching posts" for them to hold on to. Our main tanks many times do not provide the type of environment that the seahorse would be most happy in.
I found that my seahorses liked the brine shrimp that I had fortifed because they would swim right by and the seahorse could catch them. After I adjusted the flow and provided more hitching posts in his own tank, he wanders and hunts down the ghost shrimp just fine.
I hope this gives you a bit more insight into these beautiful and curious creatures.