Tri Colour Damsels

Hi Guys,

So ive recently bought 2 Tri Colour Damsels that are in my 20 gallon tank (no other fish just a few corals, a small crab and a snail).

My question is what should i house them with in a 20 gallon tank? ive looked all over the internet and it says avoid damsels at all cost but i couldnt not buy the damsels they look to good :)

Thanks