First SW fish selection for 20g QT

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My 120 reef won't be ready for fish for a while, my 20g Q-tank is cycled as of today. It has an Aquaclear 500 with 2 sponges in it for a filter.

I'd like a Hippo Tang, if I got a small one about 2" size would it be OK in the 20 gallon quarantine tank for 4 to 6 weeks while waiting for the main tank to be ready?

Also I am wondering about my fish selection, are Hippos much more delicate/sensitive than Yellow tangs, and will Hippos eat as much algae as Yellow tangs will? I like the Hippos better but I'm wondering if the Yellow tang is a more practical choice.