Usually reef conditions are not suitable for seahorses. The first thing that comes to my mind is seahorses need cool temperatures, below 75 degrees so they don't get bacterial infections. Most reefs run hotter than that. Secondly, seahorses can not be with any stinging coral and many reef fish are too aggressive to live with seahorses. Third, seahorses are a dirty fish and their wastes fosters algae growth. Seahorse tank are set up maintenance friendly to deal with the algae growth, (scraping the glass behind the rock work ect...) I do read some folks who do it but I also read more folks who run into problems as a result of it.