Could you post a pic of it for us and tell us about where you are keeping it at the moment?
First, make sure the temperature in the tank it is in is 74 degrees or lower. That is the max for tropical seahorses. If it turns out to be subtropical or temperate, the temp will need to go lower.
They need the same basic params as other fish, 0 ammonia, 0 nitrite, low nitrate. They shouldn't be kept with aggressive feeders or fast swimmers, as that can stress the SH into disease and also prevent it from getting enough food. They need to be fed 2-3 times per day, frozen mysis if they will eat it, otherwise live ghost shrimp or live mysis shrimp. Steer away from brine as their digestive systems are not complex enough to get nutrition from it. They are easily injured because they like to drag their tails and hitch to everything, so no stinging corals, anemones, clams, crabs (other than small hermits like scarlets and left-handed) , etc. Heaters and powerhead intakes also pose a danger so heater's should have a heater guard and powerhead intakes may need to be covered.
To be honest, your 30 gal does not sound like a very good home for a seahorse because they're systems need to be specialized and they are easily outcompeted for food. The anemone is especially dangerous to the SH.
There are several articles on
www.seahorse.org in their library that may help you with the basics.
