Man please do not get a seahorse. The take sooooo much to keep them healthy. For instance you can not be gone for more then 24hours or they will starve. Or the low flow and low light. Prestine water paremeters ect ect ect. I have an aquarium that I have set up right now that had been running for close to 7 months that is finally ready to bring in seahorses. In a fairly new aquarium (under 6 months) you will get a huge bloom of Copepods esp if you bought the bags of live sand. Trust me over 75% will die off. A matter of fact you may be in trouble with the mandarin you have already bought. I do not want to come off as being mean at all but I also do not want to see you have creatures dependent on pods and all of a suddon the are gone and now you are buying them to keep your tank up. Trust me they will die off.