Mandarin dragonette (or an angel)

If you are dead set on one of these fish, then I would upgrade and get them after your bigger tank is established. Wait at least 6 months to a year after upgrading for the mandarin. You can find tanks fairly cheap on craigslist, but even brand new 55 gallons are not too expensive. You can DIY the stand for pretty cheap also.

 

I had an 85g with a dwarf angel. And that tank was still not big enough for his ego. He would pick on all the fish, even a much bigger yellow tang. We also had a dragonette in the tank & he did pretty good. They constantly scour for food. We had that tank up for at least 3 years before we got the mandarin & I think it devoured the pod population. He wouldn't eat any food that we fed either. I would look more towards sand sifters that are more known to eat fish food.

 

My mandarin eats frozen! Woohoo! But yea even in my 75, i have a huge sump and tons of live rock, and i started feeding pellets, my female mandarin started to get skinny after a week of me feeding pellets every other day. I have to spot feed her frozen food or she starves. IT IS NOT EASY TO GET THEM EATING FROZEN! I say nay, i had 4-5 of them die on me because my gf kept begging me to get them, and they wouldnt take to frozen, and just starved. Terrible thing. I got lucky with the one i have had for about a year now that she started eating frozen.