Grape Caulerpa control

[Ruth]

If it is for a 29g tank you are limited in getting a fish that would control it. As has been said - most tangs love this stuff but your tank is too small. You might try a rabbit fish but again you are pushing it as far as tank size goes.
I have heard of people controlling it manually by taking each rock out and scubbing it with a stiff brush and pulling any signs of it out with tweezers - and then repeating as required.
Grape calurpa is evil IMO.