Clownfish killing new fish

So, I've had a pair of clown fish and a royal gramma for almost a year now. I want to get another fish to add some more movement into my tank but the female clown keeps tormenting and eventually killing any new fish I introduce into the tank.

How can I introduce a new one without the clown killing it?

I want to get a yellow tang

* I have heard about moving the rock around but I have lots of corals so that's not really an option for me

 

how big is the tank and what type of clowns are they?

 

You could try removing the clown while you introduce the new fish and then do some rearranging of the rock work in before you re-introduce the clown.

 

Tangs are ich-prone so if you have a tormenting clown, a tang might not be a good idea,

 

They are ocellaris clowns and the tank is 30 gallons

 

I was thinking that the tang might have a chance because it would be bigger than the clown. Is that completely wrong?

 

You're pretty much maxed out with the aggressive fish you have in a 20 gallon tank. A yellow tang would require a much bigger tank.

 

Way too small for a yellow tang. They need 75-90g+ im afraid.

 

I wouldn't add a tang if I were you. For one, your tank really isn't big enough. How big are your clowns?

 

Sorry, did you upgrade from a 20 to a 30? The same would still apply, though.