You could do a pair of regular clowns I think with no problems, they will likely fight with each other unless one is quite a bit smaller in size then the other (the larger clown is always the female). You cant have a flame angel, or any type of angel for that matter... they need at least a 55 gallon tank.
My lion has never eaten any of my fish even though I have some rather small clowns. Make sure that you acclimate him to eating frozen foods before releasing him into your tank, this shouldnt be a problem since quarentining salt water fish really isnt an option it is pretty much required. Just dont take him out of quarentine until he will accept some form of frozen food, that is unless buying a dozen ghost shrimp a week is not a problem for you (it adds up though since that is what I have to do).
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Adam
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