If you are going to do it, please spend the time to research it carefully. Here is a good site designed to minimize rookie mistakes.
“As many aquarium hobbyists know, seahorses and related species have different needs than other marine fish. This fact sheet was created to assist anyone that is interested in keeping these fascinating fish. The content herein is meant to be a guideline for new seahorse keepers based upon the experience of several hundred seahorse hobbyists, Syngnathidae researchers, and commercial breeders. WE RECOMMEND THAT ALL BEGINNING KEEPERS PURCHASE ONLY CAPTIVE BRED SEAHORSES.”