Advice given so far is solid. Fish selection for a 30g is a bit limited to pretty much nano fish. 5 small fish will probably be max just so your aware. Stocking saltwater tanks can be a bit tricky and limiting with smaller tanks.
And yes you would need to recycle the tank with saltwater. Also most fish only only tanks are fish only with live rock which i highly recommend. Live rock is a very good biological filter, plus the life you get with live rock. About 1 lb per gallon os recommended so in your case roughly 30 lbs.
29g Mixed Reef, 150w 14k Phoenix MH w/ Moonlights, Reef Octopus BH1000 HOB Skimmer, Ecotech Vortech MP10es, ReefKeeper Lite (Plus), PH Probe, Temp Probe, ATO, Carbon/GFO Reactor.