I have a 20 gallon high with some SPS,zoas, and a leather coral. I currently have a false perc and trying to get rid of my shrimp killing Arabian Dottyback. I was thinking of getting a skunk shrimp eventually. i was looking at a 6 line but i've read they can be very mean/#####y to other fish and the potentially new skunk.

Some criteria i want:
Obviously I want one that can co exist wit the existing fish
One that wont eat my coral
Colorful
Active/swims around and wont just sit around like a hawkfish

Any suggestions?

purple firefish

Azure damsel? Mine get along well and doesn't bother others. A bit on the shy side but stays out in the open once accustomed. I don't know about the size requirements though. Mine is in 60 gallon tank.

A yellowtail damsel (Chrysiptera parasema) is another peaceful species.

Gobies and dartfish/firefish are all good options.

I like the firefish for the tall tank. You might look at assessors or the Orchid Pseudochromis (Pseudochromis fridmani) as well. If you go for the pseudo, make sure it's the Fridmani or Orchid and not a "purple" pseudochromis. They get misidentified a lot and the fish that this usually occurs with is one mean little bastich.

Revaltion,
Like I said earlier, I have a dottyback now. Is this species less aggressive toward fish and shrimp? I just heard dottybacks in general were kinda biznatches.

Lakshwadeep,
I'm looking for something a little more vibrant than a yellow damsel lol.

Sorry, you didn't say anything about having one. The Orchid/Fridmani is more of a "semi-aggressive" fish and isn't known to go after shrimp. I would for sure avoid other purple fish with one.

Other alternatives are
+1 to yellow assessor
candy basslet
tobacco bass
firefish
canary wrasse
tailspot blenny

What kind of pseudochromis do you have? In your first post, only a false percula is listed in the tank. Any pseudochromis besides very few semi-aggressive species like the orchid have the potential to kill all other small fish.

Woops my bad lol. yeah the reason i want a new fish is im getting rid of an Arabian dottyback because it's killed like 2 shrimp right after they molted. And watching those little shrimpy nerds run around is more fun than watching the dottyback hid in the rocks.

The Candy basslet is pretty awesome looking just too expensive. But looks like i'll either get a yellow assessor or firefish.

Firefish are cool, I have Chalk Bass that I really like too. He's perfectly peaceful and very active. The colors range a lot with Chalk Bass from what I've seen so you can find really pretty ones. They're also relatively cheap! Don't hear about them much around here.

Black Cap Basslets are pretty but I've never owned one, I hear they're peaceful though.

I read fire fish generally stay hidden in the rock work. Anyone with some experience with this?

In all honesty, I just don't see what people have against yellow-tail damsels. They are just as bright as most of the fish commonly available in the hobby not to mention the fact that they're relatively peaceful. I think most people just have a stigma against them because they are $5 fish that are notoriously kept by beginners due their hardiness.

I agree with revelation and laks... you can't go wrong with a yellow assessor. They are a very peaceful fish. And once they get used to the tank they swim out in the open and one of their strange quirks is...... they swim upside down! And since ORA is breeding them the prices has come down significantly (around $50). They add a nice splash of yellow to the tank!

royal gramma or rainfordi goby if you have some pods you dont want anymore.

+1 to a tailspot blenny. I know you want to add a fish that swims around a lot but for future purchases this is a great and interesting fish. I liked mine a lot.

I have a firefish in my 34 tall and it swims around all day long. He did hide in the rockwork when I had my dottyback but I got rid of the dottyback and it is out all the time. As soon as the lights go off he heads into the rocks and then comes out again in the morning.

I have read that they are more prone to swim around if they have a lot of rockwork to hide in if they feel threatened.