Don't do it ! These fish are better left in the ocean. Real sensitive and have a horrible survival rate.
Having said that, your 30 g is too small for a tang or a regal. That 1 inch hippo will get way too big for a 30. What are your plans?
I found one that was eating once, but I didn't buy it anyway because I thought it was kinda small (about 3") but it was very pretty though and it was from the red sea but it wouldn't have lasted in my tank anyway so I left it alone. But if your stuck on getting one make sure it's from the red sea, and it's eating and make sure it gets a 2 weeks Q! Good luck!
I had a Regal several years back.
Right from the start, he ate like an Oscar...snapped up anything I put in the tank.
First water change I did, it was like he got mad, and never ate again.....
Beautiful fish, but extremely unpredictable and temperamental.