It depends. My cousin had 3 & 2 died after a month so my cousin bought 2 more. Soon they were dead as well. But what my cousin noticed was that the one that survived both times was the same one. My cousin bought 2 more again & again the same one survived. Apparently it was killing the other seahorses. My cousin then just kept the one & he lived for another 2 years. He couldn't be trusted. Maybe they are very territorial.