Need help finding the right wrasse(s) for my tank

[flfireman1]

+1 on the possum wrasse. Although you will find that they are usually hiding, it just their nature. They will get a little bolder once established but for the most part they tend to hide in the shadows of the aquarium. However, they are a very interesting little fish.

If the yellow coris gets too big you can always find him another home or upgrade.

Not exactly sure why you want a wrasse that "cleans the rocks"??? If you mean pest control, not exactly sure why in a 20 gallon you would have much of a problem?

 

[Hzuiel]

Is there something about small tanks that makes them less likely to get various pest worms and such?

 

[Rabidgoose]

A 20 gallon is to small for a red mandarin dragonet.